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2026-03-12serial: 8250_dw: Ensure BUSY is deassertedIlpo Järvinen
DW UART cannot write to LCR, DLL, and DLH while BUSY is asserted. Existance of BUSY depends on uart_16550_compatible, if UART HW is configured with it those registers can always be written. There currently is dw8250_force_idle() which attempts to achieve non-BUSY state by disabling FIFO, however, the solution is unreliable when Rx keeps getting more and more characters. Create a sequence of operations that ensures UART cannot keep BUSY asserted indefinitely. The new sequence relies on enabling loopback mode temporarily to prevent incoming Rx characters keeping UART BUSY. Ensure no Tx in ongoing while the UART is switches into the loopback mode (requires exporting serial8250_fifo_wait_for_lsr_thre() and adding DMA Tx pause/resume functions). According to tests performed by Adriana Nicolae <adriana@arista.com>, simply disabling FIFO or clearing FIFOs only once does not always ensure BUSY is deasserted but up to two tries may be needed. This could be related to ongoing Rx of a character (a guess, not known for sure). Therefore, retry FIFO clearing a few times (retry limit 4 is arbitrary number but using, e.g., p->fifosize seems overly large). Tests performed by others did not exhibit similar challenge but it does not seem harmful to leave the FIFO clearing loop in place for all DW UARTs with BUSY functionality. Use the new dw8250_idle_enter/exit() to do divisor writes and LCR writes. In case of plain LCR writes, opportunistically try to update LCR first and only invoke dw8250_idle_enter() if the write did not succeed (it has been observed that in practice most LCR writes do succeed without complications). This issue was first reported by qianfan Zhao who put lots of debugging effort into understanding the solution space. Fixes: c49436b657d0 ("serial: 8250_dw: Improve unwritable LCR workaround") Fixes: 7d4008ebb1c9 ("tty: add a DesignWare 8250 driver") Cc: stable <stable@kernel.org> Reported-by: qianfan Zhao <qianfanguijin@163.com> Link: https://lore.kernel.org/linux-serial/289bb78a-7509-1c5c-2923-a04ed3b6487d@163.com/ Reported-by: Adriana Nicolae <adriana@arista.com> Link: https://lore.kernel.org/linux-serial/20250819182322.3451959-1-adriana@arista.com/ Reported-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-8-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-12serial: 8250: Add late synchronize_irq() to shutdown to handle DW UART BUSYIlpo Järvinen
When DW UART is !uart_16550_compatible, it can indicate BUSY at any point (when under constant Rx pressure) unless a complex sequence of steps is performed. Any LCR write can run a foul with the condition that prevents writing LCR while the UART is BUSY, which triggers BUSY_DETECT interrupt that seems unmaskable using IER bits. Normal flow is that dw8250_handle_irq() handles BUSY_DETECT condition by reading USR register. This BUSY feature, however, breaks the assumptions made in serial8250_do_shutdown(), which runs synchronize_irq() after clearing IER and assumes no interrupts can occur after that point but then proceeds to update LCR, which on DW UART can trigger an interrupt. If serial8250_do_shutdown() releases the interrupt handler before the handler has run and processed the BUSY_DETECT condition by read the USR register, the IRQ is not deasserted resulting in interrupt storm that triggers "irq x: nobody cared" warning leading to disabling the IRQ. Add late synchronize_irq() into serial8250_do_shutdown() to ensure BUSY_DETECT from DW UART is handled before port's interrupt handler is released. Alternative would be to add DW UART specific shutdown function but it would mostly duplicate the generic code and the extra synchronize_irq() seems pretty harmless in serial8250_do_shutdown(). Fixes: 7d4008ebb1c9 ("tty: add a DesignWare 8250 driver") Cc: stable <stable@kernel.org> Reported-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-7-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-12serial: 8250_dw: Rework IIR_NO_INT handling to stop interrupt stormIlpo Järvinen
INTC10EE UART can end up into an interrupt storm where it reports IIR_NO_INT (0x1). If the storm happens during active UART operation, it is promptly stopped by IIR value change due to Rx or Tx events. However, when there is no activity, either due to idle serial line or due to specific circumstances such as during shutdown that writes IER=0, there is nothing to stop the storm. During shutdown the storm is particularly problematic because serial8250_do_shutdown() calls synchronize_irq() that will hang in waiting for the storm to finish which never happens. This problem can also result in triggering a warning: irq 45: nobody cared (try booting with the "irqpoll" option) [...snip...] handlers: serial8250_interrupt Disabling IRQ #45 Normal means to reset interrupt status by reading LSR, MSR, USR, or RX register do not result in the UART deasserting the IRQ. Add a quirk to INTC10EE UARTs to enable Tx interrupts if UART's Tx is currently empty and inactive. Rework IIR_NO_INT to keep track of the number of consecutive IIR_NO_INT, and on fourth one perform the quirk. Enabling Tx interrupts should change IIR value from IIR_NO_INT to IIR_THRI which has been observed to stop the storm. Fixes: e92fad024929 ("serial: 8250_dw: Add ACPI ID for Granite Rapids-D UART") Cc: stable <stable@kernel.org> Reported-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-6-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-12serial: 8250_dw: Rework dw8250_handle_irq() locking and IIR handlingIlpo Järvinen
dw8250_handle_irq() takes port's lock multiple times with no good reason to release it in between and calls serial8250_handle_irq() that also takes port's lock. Take port's lock only once in dw8250_handle_irq() and use serial8250_handle_irq_locked() to avoid releasing port's lock in between. As IIR_NO_INT check in serial8250_handle_irq() was outside of port's lock, it has to be done already in dw8250_handle_irq(). DW UART can, in addition to IIR_NO_INT, report BUSY_DETECT (0x7) which collided with the IIR_NO_INT (0x1) check in serial8250_handle_irq() (because & is used instead of ==) meaning that no other work is done by serial8250_handle_irq() during an BUSY_DETECT interrupt. This allows reorganizing code in dw8250_handle_irq() to do both IIR_NO_INT and BUSY_DETECT handling right at the start simplifying the logic. Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Cc: stable <stable@kernel.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-5-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-12serial: 8250: Add serial8250_handle_irq_locked()Ilpo Järvinen
8250_port exports serial8250_handle_irq() to HW specific 8250 drivers. It takes port's lock within but a HW specific 8250 driver may want to take port's lock itself, do something, and then call the generic handler in 8250_port but to do that, the caller has to release port's lock for no good reason. Introduce serial8250_handle_irq_locked() which a HW specific driver can call while already holding port's lock. As this is new export, put it straight into a namespace (where all 8250 exports should eventually be moved). Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Cc: stable <stable@kernel.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-4-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-12serial: 8250_dw: Avoid unnecessary LCR writesIlpo Järvinen
When DW UART is configured with BUSY flag, LCR writes may not always succeed which can make any LCR write complex and very expensive. Performing write directly can trigger IRQ and the driver has to perform complex and distruptive sequence while retrying the write. Therefore, it's better to avoid doing LCR write that would not change the value of the LCR register. Add LCR write avoidance code into the 8250_dw driver's .serial_out() functions. Reported-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Cc: stable <stable@kernel.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-3-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-12serial: 8250: Protect LCR write in shutdownIlpo Järvinen
The 8250_dw driver needs to potentially perform very complex operations during LCR writes because its BUSY handling prevents updates to LCR while UART is BUSY (which is not fully under our control without those complex operations). Thus, LCR writes should occur under port's lock. Move LCR write under port's lock in serial8250_do_shutdown(). Also split the LCR RMW so that the logic is on a separate line for clarity. Reported-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Bandal, Shankar <shankar.bandal@intel.com> Tested-by: Murthy, Shanth <shanth.murthy@intel.com> Cc: stable <stable@kernel.org> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://patch.msgid.link/20260203171049.4353-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-12serial: 8250_pci: add support for the AX99100Martin Roukala (né Peres)
This is found in popular brands such as StarTech.com or Delock, and has been a source of frustration to quite a few people, if I can trust Amazon comments complaining about Linux support via the official out-of-the-tree driver. Signed-off-by: Martin Roukala (né Peres) <martin.roukala@mupuf.org> Cc: stable <stable@kernel.org> Link: https://patch.msgid.link/20260309-8250_pci_ax99100-v1-1-3328bdfd8e94@mupuf.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-12serial: core: fix infinite loop in handle_tx() for PORT_UNKNOWNJiayuan Chen
uart_write_room() and uart_write() behave inconsistently when xmit_buf is NULL (which happens for PORT_UNKNOWN ports that were never properly initialized): - uart_write_room() returns kfifo_avail() which can be > 0 - uart_write() checks xmit_buf and returns 0 if NULL This inconsistency causes an infinite loop in drivers that rely on tty_write_room() to determine if they can write: while (tty_write_room(tty) > 0) { written = tty->ops->write(...); // written is always 0, loop never exits } For example, caif_serial's handle_tx() enters an infinite loop when used with PORT_UNKNOWN serial ports, causing system hangs. Fix by making uart_write_room() also check xmit_buf and return 0 if it's NULL, consistent with uart_write(). Reproducer: https://gist.github.com/mrpre/d9a694cc0e19828ee3bc3b37983fde13 Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com> Cc: stable <stable@kernel.org> Link: https://patch.msgid.link/20260204074327.226165-1-jiayuan.chen@linux.dev Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-12serial: uartlite: fix PM runtime usage count underflow on probeMaciej Andrzejewski ICEYE
ulite_probe() calls pm_runtime_put_autosuspend() at the end of probe without holding a corresponding PM runtime reference for non-console ports. During ulite_assign(), uart_add_one_port() triggers uart_configure_port() which calls ulite_pm() via uart_change_pm(). For non-console ports, the UART core performs a balanced get/put cycle: uart_change_pm(ON) -> ulite_pm() -> pm_runtime_get_sync() +1 uart_change_pm(OFF) -> ulite_pm() -> pm_runtime_put_autosuspend() -1 This leaves no spare reference for the pm_runtime_put_autosuspend() at the end of probe. The PM runtime core prevents the count from actually going below zero, and instead triggers a "Runtime PM usage count underflow!" warning. For console ports the bug is masked: the UART core skips the uart_change_pm(OFF) call, so the UART core's unbalanced get happens to pair with probe's trailing put. Add pm_runtime_get_noresume() before pm_runtime_enable() to take an explicit probe-owned reference that the trailing pm_runtime_put_autosuspend() can release. This ensures a correct usage count regardless of whether the port is a console. Fixes: 5bbe10a6942d ("tty: serial: uartlite: Add runtime pm support") Cc: stable <stable@kernel.org> Signed-off-by: Maciej Andrzejewski ICEYE <maciej.andrzejewski@m-works.net> Link: https://patch.msgid.link/20260305123746.4152800-1-maciej.andrzejewski@m-works.net Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-12serial: 8250: always disable IRQ during THRE testPeng Zhang
commit 039d4926379b ("serial: 8250: Toggle IER bits on only after irq has been set up") moved IRQ setup before the THRE test, in combination with commit 205d300aea75 ("serial: 8250: change lock order in serial8250_do_startup()") the interrupt handler can run during the test and race with its IIR reads. This can produce wrong THRE test results and cause spurious registration of the serial8250_backup_timeout timer. Unconditionally disable the IRQ for the short duration of the test and re-enable it afterwards to avoid the race. Fixes: 039d4926379b ("serial: 8250: Toggle IER bits on only after irq has been set up") Depends-on: 205d300aea75 ("serial: 8250: change lock order in serial8250_do_startup()") Cc: stable <stable@kernel.org> Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Alban Bedel <alban.bedel@lht.dlh.de> Tested-by: Maximilian Lueer <maximilian.lueer@lht.dlh.de> Link: https://patch.msgid.link/20260224121639.579404-1-alban.bedel@lht.dlh.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-03-12serial: 8250: Fix TX deadlock when using DMARaul E Rangel
`dmaengine_terminate_async` does not guarantee that the `__dma_tx_complete` callback will run. The callback is currently the only place where `dma->tx_running` gets cleared. If the transaction is canceled and the callback never runs, then `dma->tx_running` will never get cleared and we will never schedule new TX DMA transactions again. This change makes it so we clear `dma->tx_running` after we terminate the DMA transaction. This is "safe" because `serial8250_tx_dma_flush` is holding the UART port lock. The first thing the callback does is also grab the UART port lock, so access to `dma->tx_running` is serialized. Fixes: 9e512eaaf8f4 ("serial: 8250: Fix fifo underflow on flush") Cc: stable <stable@kernel.org> Signed-off-by: Raul E Rangel <rrangel@google.com> Link: https://patch.msgid.link/20260209135815.1.I16366ecb0f62f3c96fe3dd5763fcf6f3c2b4d8cd@changeid Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-02-22Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL usesKees Cook
Conversion performed via this Coccinelle script: // SPDX-License-Identifier: GPL-2.0-only // Options: --include-headers-for-types --all-includes --include-headers --keep-comments virtual patch @gfp depends on patch && !(file in "tools") && !(file in "samples")@ identifier ALLOC = {kmalloc_obj,kmalloc_objs,kmalloc_flex, kzalloc_obj,kzalloc_objs,kzalloc_flex, kvmalloc_obj,kvmalloc_objs,kvmalloc_flex, kvzalloc_obj,kvzalloc_objs,kvzalloc_flex}; @@ ALLOC(... - , GFP_KERNEL ) $ make coccicheck MODE=patch COCCI=gfp.cocci Build and boot tested x86_64 with Fedora 42's GCC and Clang: Linux version 6.19.0+ (user@host) (gcc (GCC) 15.2.1 20260123 (Red Hat 15.2.1-7), GNU ld version 2.44-12.fc42) #1 SMP PREEMPT_DYNAMIC 1970-01-01 Linux version 6.19.0+ (user@host) (clang version 20.1.8 (Fedora 20.1.8-4.fc42), LLD 20.1.8) #1 SMP PREEMPT_DYNAMIC 1970-01-01 Signed-off-by: Kees Cook <kees@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2026-02-21Convert more 'alloc_obj' cases to default GFP_KERNEL argumentsLinus Torvalds
This converts some of the visually simpler cases that have been split over multiple lines. I only did the ones that are easy to verify the resulting diff by having just that final GFP_KERNEL argument on the next line. Somebody should probably do a proper coccinelle script for this, but for me the trivial script actually resulted in an assertion failure in the middle of the script. I probably had made it a bit _too_ trivial. So after fighting that far a while I decided to just do some of the syntactically simpler cases with variations of the previous 'sed' scripts. The more syntactically complex multi-line cases would mostly really want whitespace cleanup anyway. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2026-02-21Convert 'alloc_flex' family to use the new default GFP_KERNEL argumentLinus Torvalds
This is the exact same thing as the 'alloc_obj()' version, only much smaller because there are a lot fewer users of the *alloc_flex() interface. As with alloc_obj() version, this was done entirely with mindless brute force, using the same script, except using 'flex' in the pattern rather than 'objs*'. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2026-02-21Convert 'alloc_obj' family to use the new default GFP_KERNEL argumentLinus Torvalds
This was done entirely with mindless brute force, using git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' | xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/' to convert the new alloc_obj() users that had a simple GFP_KERNEL argument to just drop that argument. Note that due to the extreme simplicity of the scripting, any slightly more complex cases spread over multiple lines would not be triggered: they definitely exist, but this covers the vast bulk of the cases, and the resulting diff is also then easier to check automatically. For the same reason the 'flex' versions will be done as a separate conversion. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2026-02-21treewide: Replace kmalloc with kmalloc_obj for non-scalar typesKees Cook
This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook <kees@kernel.org>
2026-02-17Merge tag 'tty-7.0-rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty / serial driver updates from Greg KH: "Here is the small amount of tty and serial driver updates for 7.0-rc1. Nothing major in here at all, just some driver updates and minor tweaks and cleanups including: - sh-sci serial driver updates - 8250 driver updates - attempt to make the tty ports have their own workqueue, but was reverted after testing found it to have problems on some platforms. This will probably come back for 7.1 after it has been reworked and resubmitted - other tiny tty driver changes All of these have been in linux-next for a while with no reported problems" * tag 'tty-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (49 commits) Revert "tty: tty_port: add workqueue to flip TTY buffer" tty: tty_port: add workqueue to flip TTY buffer serial: 8250_pci: Remove custom deprecated baud setting routine serial: 8250_omap: Remove custom deprecated baud setting routine dt-bindings: serial: renesas,scif: Document RZ/G3L SoC serial: 8250: omap: set out-of-band wakeup if wakeup pinctrl exists tty: hvc-iucv: Remove KMSG_COMPONENT macro dt-bindings: serial: google,goldfish-tty: Convert to DT schema dt-bindings: serial: sh-sci: Fold single-entry compatibles into enum serial: 8250: 8250_omap.c: Clear DMA RX running status only after DMA termination is done serial: 8250: 8250_omap.c: Add support for handling UART error conditions serial: SH_SCI: improve "DMA support" prompt serial: Kconfig: fix ordering of entries for menu display serial: 8250: fix ordering of entries for menu display serial: imx: change SERIAL_IMX_CONSOLE to bool 8250_men_mcb: drop unneeded MODULE_ALIAS serial: men_z135_uart: drop unneeded MODULE_ALIAS dt-bindings: serial: renesas,rsci: Document RZ/V2H(P) and RZ/V2N SoCs serial: rsci: Convert to FIELD_MODIFY() dt-bindings: serial: 8250: add SpacemiT K3 UART compatible ...
2026-01-30serial: pic32_uart: update include to use pic32.h from platform_dataBrian Masney
Use the linux/platform_data/pic32.h include instead of asm/mach-pic32/pic32.h so that the asm variant can be dropped. This is in preparation for allowing some drivers to be compiled on other architectures with COMPILE_TEST enabled. Signed-off-by: Brian Masney <bmasney@redhat.com> Reviewed-by: Jiri Slaby <jirislaby@kernel.org> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
2026-01-23serial: 8250_pci: Remove custom deprecated baud setting routineAndy Shevchenko
As comments mentioned this is old (and actually deprecated) interface to set custom baud rates. This interface has limitations as it only allows to set a single opaque value called "custom_divisor". If the HW needs more complex settings (like fractional divisor) it must somehow encode this. This is horrid interface that is very driver specific and not flexible. Meanwhile Linux has established way to set free baud rate settings via BOTHER [1]. With all this being said, remove deprecated interface for good. Link: https://stackoverflow.com/questions/12646324/how-can-i-set-a-custom-baud-rate-on-linux [1] Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://patch.msgid.link/20260122102349.2395423-3-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-23serial: 8250_omap: Remove custom deprecated baud setting routineAndy Shevchenko
As comments mentioned this is old (and actually deprecated) interface to set custom baud rates. This interface has limitations as it only allows to set a single opaque value called "custom_divisor". If the HW needs more complex settings (like fractional divisor) it must somehow encode this. This is horrid interface that is very driver specific and not flexible. Meanwhile Linux has established way to set free baud rate settings via BOTHER [1]. With all this being said, remove deprecated interface for good. Link: https://stackoverflow.com/questions/12646324/how-can-i-set-a-custom-baud-rate-on-linux [1] Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://patch.msgid.link/20260122102349.2395423-2-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-23serial: 8250: omap: set out-of-band wakeup if wakeup pinctrl existsKendall Willis
In TI K3 SoCs, I/O daisy chaining is used to allow wakeup from UART when the UART controller is off. Set UART device as wakeup capable using out-of-band wakeup if the 'wakeup' pinctrl state exists and the device may wakeup. Reviewed-by: Dhruva Gole <d-gole@ti.com> Signed-off-by: Kendall Willis <k-willis@ti.com> Link: https://patch.msgid.link/20260116-uart-wakeup-v2-1-0078ae9996e4@ti.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-23serial: Fix not set tty->port race conditionKrzysztof Kozlowski
Revert commit bfc467db60b7 ("serial: remove redundant tty_port_link_device()") because the tty_port_link_device() is not redundant: the tty->port has to be confured before we call uart_configure_port(), otherwise user-space can open console without TTY linked to the driver. This tty_port_link_device() was added explicitly to avoid this exact issue in commit fb2b90014d78 ("tty: link tty and port before configuring it as console"), so offending commit basically reverted the fix saying it is redundant without addressing the actual race condition presented there. Reproducible always as tty->port warning on Qualcomm SoC with most of devices disabled, so with very fast boot, and one serial device being the console: printk: legacy console [ttyMSM0] enabled printk: legacy console [ttyMSM0] enabled printk: legacy bootconsole [qcom_geni0] disabled printk: legacy bootconsole [qcom_geni0] disabled ------------[ cut here ]------------ tty_init_dev: ttyMSM driver does not set tty->port. This would crash the kernel. Fix the driver! WARNING: drivers/tty/tty_io.c:1414 at tty_init_dev.part.0+0x228/0x25c, CPU#2: systemd/1 Modules linked in: socinfo tcsrcc_eliza gcc_eliza sm3_ce fuse ipv6 CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: G S 6.19.0-rc4-next-20260108-00024-g2202f4d30aa8 #73 PREEMPT Tainted: [S]=CPU_OUT_OF_SPEC Hardware name: Qualcomm Technologies, Inc. Eliza (DT) ... tty_init_dev.part.0 (drivers/tty/tty_io.c:1414 (discriminator 11)) (P) tty_open (arch/arm64/include/asm/atomic_ll_sc.h:95 (discriminator 3) drivers/tty/tty_io.c:2073 (discriminator 3) drivers/tty/tty_io.c:2120 (discriminator 3)) chrdev_open (fs/char_dev.c:411) do_dentry_open (fs/open.c:962) vfs_open (fs/open.c:1094) do_open (fs/namei.c:4634) path_openat (fs/namei.c:4793) do_filp_open (fs/namei.c:4820) do_sys_openat2 (fs/open.c:1391 (discriminator 3)) ... Starting Network Name Resolution... Apparently the flow with this small Yocto-based ramdisk user-space is: driver (qcom_geni_serial.c): user-space: ============================ =========== qcom_geni_serial_probe() uart_add_one_port() serial_core_register_port() serial_core_add_one_port() uart_configure_port() register_console() | | open console | ... | tty_init_dev() | driver->ports[idx] is NULL | tty_port_register_device_attr_serdev() tty_port_link_device() <- set driver->ports[idx] Fixes: bfc467db60b7 ("serial: remove redundant tty_port_link_device()") Cc: stable@vger.kernel.org Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com> Reviewed-by: Jiri Slaby <jirislaby@kernel.org> Link: https://patch.msgid.link/20260123072139.53293-2-krzysztof.kozlowski@oss.qualcomm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-16serial: 8250_pci: Fix broken RS485 for F81504/508/512Marnix Rijnart
Fintek F81504/508/512 can support both RTS_ON_SEND and RTS_AFTER_SEND, but pci_fintek_rs485_supported only announces the former. This makes it impossible to unset SER_RS485_RTS_ON_SEND from userspace because of uart_sanitize_serial_rs485(). Some devices with these chips need RTS low on TX, so they are effectively broken. Fix this by announcing the support for SER_RS485_RTS_AFTER_SEND, similar to commit 068d35a7be65 ("serial: sc16is7xx: announce support for SER_RS485_RTS_ON_SEND"). Fixes: 4afeced55baa ("serial: core: fix sanitizing check for RTS settings") Cc: stable <stable@kernel.org> Signed-off-by: Marnix Rijnart <marnix.rijnart@iwell.eu> Link: https://patch.msgid.link/20260112000931.61703-1-marnix.rijnart@iwell.eu Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-16serial: qcom_geni: Fix BT failure regression on RB2 platformPraveen Talari
Commit 10904d725f6e ("serial: qcom-geni: Enable PM runtime for serial driver") caused BT init to fail during bootup on the RB2 platform, preventing proper BT initialization. However, BT works correctly after bootup completes. The issue occurs when runtime PM is enabled and uart_add_one_port() is called before wakeup IRQ setup. The uart_add_one_port() call activates the device through runtime PM, which configures GPIOs to the "qup_x" pinmux function during runtime resume. When wakeup IRQ registration happens afterward using dev_pm_set_dedicated_wake_irq(), these GPIOs are reset back to the "gpio" pinmux function, which impacts the RX GPIO and leads to Bluetooth failures. Fix this by ensuring wakeup IRQ setup is completed before calling uart_add_one_port() to prevent the pinmux function conflict. Fixes: 10904d725f6e ("serial: qcom-geni: Enable PM runtime for serial driver") Reported-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> Closes: https://lore.kernel.org/all/20251110101043.2108414-4-praveen.talari@oss.qualcomm.com/ Tested-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com> Link: https://patch.msgid.link/20260108041006.1874757-1-praveen.talari@oss.qualcomm.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-16serial: 8250: 8250_omap.c: Clear DMA RX running status only after DMA ↵Moteen Shah
termination is done Clear rx_running flag only after DMA teardown polling completes. In the previous implementation the flag was being cleared while hardware teardown was still in progress, creating a mismatch between software state (flag = 0, "ready") and hardware state (still terminating). Signed-off-by: Moteen Shah <m-shah@ti.com> Link: https://patch.msgid.link/20260112081829.63049-3-m-shah@ti.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-16serial: 8250: 8250_omap.c: Add support for handling UART error conditionsMoteen Shah
The DMA IRQ handler does not accounts for the overrun(OE) or any other errors being reported by the IP before triggering a DMA transaction which leads to the interrupts not being handled resulting into an IRQ storm. The way to handle OE is to: 1. Reset the RX FIFO. 2. Read the UART_RESUME register, which clears the internal flag Earlier, the driver issued DMA transations even in case of OE which shouldn't be done according to the OE handling mechanism mentioned above, as we are resetting the FIFO's, refer section: "12.1.6.4.8.1.3.6 Overrun During Receive" [0]. [0] https://www.ti.com/lit/pdf/spruiu1 Signed-off-by: Moteen Shah <m-shah@ti.com> Link: https://patch.msgid.link/20260112081829.63049-2-m-shah@ti.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-16serial: SH_SCI: improve "DMA support" promptRandy Dunlap
Having a prompt of "DMA support" suddenly appear during a "make oldconfig" can be confusing. Add a little helpful text to the prompt message. Fixes: 73a19e4c0301 ("serial: sh-sci: Add DMA support.") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Link: https://patch.msgid.link/20260110232643.3533351-5-rdunlap@infradead.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-16serial: Kconfig: fix ordering of entries for menu displayRandy Dunlap
Improve the "Non-8250 serial port support" menu so that entries in it are displayed in a better order (_CONSOLE after its driver) and so that intervening symbols don't break up the dependency list, allowing menu entries to be displayed with proper indentation. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Link: https://patch.msgid.link/20260110232643.3533351-4-rdunlap@infradead.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-16serial: 8250: fix ordering of entries for menu displayRandy Dunlap
Improve the "8250/16550 serial support" menu so that entries in it are displayed in a better order (reorder a few symbols) and so that intervening symbols don't break up the dependency list, allowing menu entries to be displayed with proper indentation. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Link: https://patch.msgid.link/20260110232643.3533351-3-rdunlap@infradead.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-16serial: imx: change SERIAL_IMX_CONSOLE to boolRandy Dunlap
SERIAL_IMX_CONSOLE is a build option for the imx driver (SERIAL_IMX). It does not build a separate console driver file, so it can't be built as a module since it isn't built at all. Change the Kconfig symbol from tristate to bool and update the help text accordingly. Fixes: 0db4f9b91c86 ("tty: serial: imx: enable imx serial console port as module") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Link: https://patch.msgid.link/20260110232643.3533351-2-rdunlap@infradead.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-168250_men_mcb: drop unneeded MODULE_ALIASJose Javier Rodriguez Barbarin
Since commit 1f4ea4838b13 ("mcb: Add missing modpost build support") the MODULE_ALIAS() is redundant as the module alias is now automatically generated from the MODULE_DEVICE_TABLE(). Remove the explicit alias. No functional change intended. Reviewed-by: Jorge Sanjuan Garcia <dev-jorge.sanjuangarcia@duagon.com> Signed-off-by: Jose Javier Rodriguez Barbarin <dev-josejavier.rodriguez@duagon.com> Link: https://patch.msgid.link/20260108134110.25278-3-dev-josejavier.rodriguez@duagon.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2026-01-16serial: men_z135_uart: drop unneeded MODULE_ALIASJose Javier Rodriguez Barbarin
Since commit 1f4ea4838b13 ("mcb: Add missing modpost build support") the MODULE_ALIAS() is redundant as the module alias is now automatically generated from the MODULE_DEVICE_TABLE(). Remove the explicit alias. No functional change intended. Reviewed-by: Jorge Sanjuan Garcia <dev-jorge.sanjuangarcia@duagon.com> Signed-off-by: Jose Javier Rodriguez Barbarin <dev-josejavier.rodriguez@duagon.com> Link: https://patch.msgid.link/20260108134110.25278-2-dev-josejavier.rodriguez@duagon.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-29Merge 6.19-rc3 into tty-nextGreg Kroah-Hartman
We need the serial fixes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-23serial: xilinx_uartps: fix rs485 delay_rts_after_sendj.turek
RTS line control with delay should be triggered when there is no more bytes in kfifo and hardware buffer is empty. Without this patch RTS control is scheduled right after feeding hardware buffer and this is too early. RTS line may change state before hardware buffer is empty. With this patch delayed RTS state change is triggered when function cdns_uart_handle_tx is called from cdns_uart_isr on CDNS_UART_IXR_TXEMPTY exactly when hardware completed transmission Fixes: fccc9d9233f9 ("tty: serial: uartps: Add rs485 support to uartps driver") Cc: stable <stable@kernel.org> Link: https://patch.msgid.link/20251221103221.1971125-1-jakub.turek@elsta.tech Signed-off-by: Jakub Turek <jakub.turek@elsta.tech> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-23serial: sh-sci: Check that the DMA cookie is validClaudiu Beznea
The driver updates struct sci_port::tx_cookie to zero right before the TX work is scheduled, or to -EINVAL when DMA is disabled. dma_async_is_complete(), called through dma_cookie_status() (and possibly through dmaengine_tx_status()), considers cookies valid only if they have values greater than or equal to 1. Passing zero or -EINVAL to dmaengine_tx_status() before any TX DMA transfer has started leads to an incorrect TX status being reported, as the cookie is invalid for the DMA subsystem. This may cause long wait times when the serial device is opened for configuration before any TX activity has occurred. Check that the TX cookie is valid before passing it to dmaengine_tx_status(). Fixes: 7cc0e0a43a91 ("serial: sh-sci: Check if TX data was written to device in .tx_empty()") Cc: stable <stable@kernel.org> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com> Link: https://patch.msgid.link/20251217135759.402015-1-claudiu.beznea.uj@bp.renesas.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-23serial: core: Fix serial device initializationAlexander Stein
During restoring sysfs fwnode information the information of_node_reused was dropped. This was previously set by device_set_of_node_from_dev(). Add it back manually Fixes: 24ec03cc5512 ("serial: core: Restore sysfs fwnode information") Cc: stable <stable@kernel.org> Suggested-by: Cosmin Tanislav <demonsingur@gmail.com> Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com> Tested-by: Michael Walle <mwalle@kernel.org> Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> Tested-by: Cosmin Tanislav <demonsingur@gmail.com> Link: https://patch.msgid.link/20251219152813.1893982-1-alexander.stein@ew.tq-group.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-23serial: rsci: Convert to FIELD_MODIFY()Geert Uytterhoeven
Use the FIELD_MODIFY() helper instead of open-coding the same operation. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Link: https://patch.msgid.link/ada3faf4698155a618ae6371b35eab121eb8b19c.1766411924.git.geert+renesas@glider.be Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-17serial: 8250: longson: Fix NULL vs IS_ERR() bug in probeDan Carpenter
The devm_platform_get_and_ioremap_resource() function never returns NULL, it returns error pointers. Fix the error checking to match. Fixes: 25e95d763176 ("serial: 8250: Add Loongson uart driver support") Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org> Link: https://patch.msgid.link/aSsIa3KdAlXh5uQC@stanley.mountain Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-17serial: core: Restore sysfs fwnode informationAndy Shevchenko
The change that restores sysfs fwnode information does it only for OF cases. Update the fix to cover all possible types of fwnodes. Fixes: d36f0e9a0002 ("serial: core: restore of_node information in sysfs") Cc: stable <stable@kernel.org> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://patch.msgid.link/20251127163650.2942075-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-17serial: sh-sci: Add support for RZ/G3E RSCIBiju Das
Add support for RZ/G3E RSCI. RSCI IP found on the RZ/G3E SoC is similar to RZ/T2H, but it has a 32-stage FIFO. It has 6 clocks(5 module clocks + 1 external clock) instead of 3 clocks(2 module clocks + 1 external clock) on T2H, has 6 irqs compared to 4 on RZ/T2H and has multiple resets. Add support for the hardware flow control. Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Link: https://patch.msgid.link/20251129164325.209213-18-biju.das.jz@bp.renesas.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-17serial: rsci: Rename early_console data, port_params and callback() namesBiju Das
Rename rsci_early_console_setup()->rsci_rzt2h_early_console_setup(), the early_console data of_sci_rsci_data->of_rsci_rzt2h_data and the port_params rsci_port_params->rsci_rzt2h_port_params to support RZ/G3E RSCI that uses different data and callback(). Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Link: https://patch.msgid.link/20251129164325.209213-17-biju.das.jz@bp.renesas.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-17serial: sh-sci: Add finish_console_write() callbackBiju Das
Add finish_console_write() callback as RZ/G3E RSCI IP needs special handling compared to other SoCs. Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Link: https://patch.msgid.link/20251129164325.209213-16-biju.das.jz@bp.renesas.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-17serial: sh-sci: Make sci_scbrr_calc() publicBiju Das
Make the function sci_scbrr_calc() public for code reuse to support RZ/G3E RSCI IP. Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Link: https://patch.msgid.link/20251129164325.209213-15-biju.das.jz@bp.renesas.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-17serial: sh-sci: Add support for RZ/G3E RSCI clksBiju Das
RZ/G3E RSCI has 6 clocks (5 module clocks + 1 external clock). Add support for the module clocks. Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Link: https://patch.msgid.link/20251129164325.209213-14-biju.das.jz@bp.renesas.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-17serial: sh-sci: Add RSCI_PORT_SCIF32 port IDBiju Das
The RZ/G3E RSCI IP has 32-stage FIFO compared to 16-stage FIFO on RZ/T2H. Add RSCI_PORT_SCIF32 port ID to differentiate it from RZ/T2H RSCI and update sci_is_rsci_type() and sci_is_fifo_type() Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Link: https://patch.msgid.link/20251129164325.209213-13-biju.das.jz@bp.renesas.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-17serial: sh-sci: Rename port SCI_PORT_RSCI->RSCI_PORT_SCIF16Biju Das
Rename port SCI_PORT_RSCI->RSCI_PORT_SCIF16 to differentiate it from RZ/G3E port that has 32-stage FIFO. Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Link: https://patch.msgid.link/20251129164325.209213-12-biju.das.jz@bp.renesas.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-17serial: sh-sci: Add sci_is_rsci_type()Biju Das
Add sci_is_rsci_type() for RSCI port type. This will simplify the code when the support added for RSCI_PORT_SCIF32 private PORT type. Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Link: https://patch.msgid.link/20251129164325.209213-11-biju.das.jz@bp.renesas.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-17serial: sh-sci: Use devm_reset_control_array_get_exclusive()Biju Das
Replace devm_*_get_exclusive()->devm_*_array_get_exclusive() to support existing SoCs along with RZ/G3E as RZ/G3E has 2 resets. Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Link: https://patch.msgid.link/20251129164325.209213-10-biju.das.jz@bp.renesas.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-12-17serial: rsci: Drop unused TDR registerBiju Das
Drop the unused TDR register-related macros. Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com> Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Link: https://patch.msgid.link/20251129164325.209213-9-biju.das.jz@bp.renesas.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
generated by cgit v1.3 (git 2.53.0) at 2026-04-03 03:06:25 +0000