user/sven/linux.git/include/linux/platform_data/dma-dw.h, branch v5.4.270

dmaengine: dw: Add DMA-channels mask cell support

2020-10-29T08:58:09Z

[ Upstream commit e8ee6c8cb61b676f1a2d6b942329e98224bd8ee9 ] DW DMA IP-core provides a way to synthesize the DMA controller with channels having different parameters like maximum burst-length, multi-block support, maximum data width, etc. Those parameters both explicitly and implicitly affect the channels performance. Since DMA slave devices might be very demanding to the DMA performance, let's provide a functionality for the slaves to be assigned with DW DMA channels, which performance according to the platform engineer fulfill their requirements. After this patch is applied it can be done by passing the mask of suitable DMA-channels either directly in the dw_dma_slave structure instance or as a fifth cell of the DMA DT-property. If mask is zero or not provided, then there is no limitation on the channels allocation. For instance Baikal-T1 SoC is equipped with a DW DMAC engine, which first two channels are synthesized with max burst length of 16, while the rest of the channels have been created with max-burst-len=4. It would seem that the first two channels must be faster than the others and should be more preferable for the time-critical DMA slave devices. In practice it turned out that the situation is quite the opposite. The channels with max-burst-len=4 demonstrated a better performance than the channels with max-burst-len=16 even when they both had been initialized with the same settings. The performance drop of the first two DMA-channels made them unsuitable for the DW APB SSI slave device. No matter what settings they are configured with, full-duplex SPI transfers occasionally experience the Rx FIFO overflow. It means that the DMA-engine doesn't keep up with incoming data pace even though the SPI-bus is enabled with speed of 25MHz while the DW DMA controller is clocked with 50MHz signal. There is no such problem has been noticed for the channels synthesized with max-burst-len=4. Signed-off-by: Serge Semin Link: https://lore.kernel.org/r/20200731200826.9292-6-Sergey.Semin@baikalelectronics.ru Signed-off-by: Vinod Koul Signed-off-by: Sasha Levin

dmaengine: dw: convert to SPDX identifiers

2019-01-07T12:27:13Z

This patch updates license to use SPDX-License-Identifier instead of verbose license text. Signed-off-by: Andy Shevchenko Signed-off-by: Vinod Koul

dmaengine: dw: Split DW and iDMA 32-bit operations

2019-01-07T12:27:13Z

Here is a kinda big refactoring that should have been done in the first place, when Intel iDMA 32-bit support appeared. It splits operations which are different to Synopsys DesignWare and Intel iDMA 32-bit controllers. No functional change intended. Signed-off-by: Andy Shevchenko Signed-off-by: Vinod Koul

dmaengine: dw: Remove unused internal property

2019-01-07T12:27:13Z

All known devices, which use DT for configuration, support memory-to-memory transfers. So enable it by default. The rest two cases, i.e. Intel Quark and PPC460ex, instantiate DMA driver and use its channels exclusively for hardware, which means there is no available channel for any other purposes anyway. Signed-off-by: Andy Shevchenko Signed-off-by: Vinod Koul

dmaengine: dw: Remove misleading is_private property

2019-01-07T12:27:13Z

The commit a9ddb575d6d6 ("dmaengine: dw_dmac: Enhance device tree support") introduces is_private property in uncertain understanding what does it mean. First of all, documentation defines DMA_PRIVATE capability as Documentation/crypto/async-tx-api.txt: The DMA_PRIVATE capability flag is used to tag dma devices that should not be used by the general-purpose allocator. It can be set at initialization time if it is known that a channel will always be private. Alternatively, it is set when dma_request_channel() finds an unused "public" channel. A couple caveats to note when implementing a driver and consumer: 1/ Once a channel has been privately allocated it will no longer be considered by the general-purpose allocator even after a call to dma_release_channel(). 2/ Since capabilities are specified at the device level a dma_device with multiple channels will either have all channels public, or all channels private. Documentation/driver-api/dmaengine/provider.rst: - DMA_PRIVATE The devices only supports slave transfers, and as such isn't available for async transfers. The capability had been introduced by the commit 59b5ec21446b ("dmaengine: introduce dma_request_channel and private channels") and some code didn't changed from that times ever. Taking into consideration above and the fact that on all known platforms Synopsys DesignWare DMA engine is attached to serve slave transfers, the DMA_PRIVATE capability must be enabled for this device unconditionally. Otherwise, as rightfully noticed in drivers/dma/at_xdmac.c: /* * Without DMA_PRIVATE the driver is not able to allocate more than * one channel, second allocation fails in private_candidate. */ because of of a caveats mentioned in above documentation excerpts. So, remove conditional around DMA_PRIVATE followed by removal leftovers. If someone wonders, DMA_PRIVATE can be not used if and only if the all channels of the DMA controller are supposed to serve memory-to-memory like operations. For example, EP93xx has two controllers, one of which can only perform memory-to-memory transfers Note, this change doesn't affect dmatest to be able to test such controllers. Cc: Greg Kroah-Hartman (maintainer:SERIAL DRIVERS) Cc: Dan Williams Signed-off-by: Andy Shevchenko Acked-by: Greg Kroah-Hartman Signed-off-by: Vinod Koul

dmaengine: dw-dmac: implement dma protection control setting

2018-11-24T14:37:22Z

This patch adds a new device-tree property that allows to specify the dma protection control bits for the all of the DMA controller's channel uniformly. Setting the "correct" bits can have a huge impact on the PPC460EX and APM82181 that use this DMA engine in combination with a DesignWare' SATA-II core (sata_dwc_460ex driver). In the OpenWrt Forum, the user takimata reported that: |It seems your patch unleashed the full power of the SATA port. |Where I was previously hitting a really hard limit at around |82 MB/s for reading and 27 MB/s for writing, I am now getting this: | |root@OpenWrt:/mnt# time dd if=/dev/zero of=tempfile bs=1M count=1024 |1024+0 records in |1024+0 records out |real 0m 13.65s |user 0m 0.01s |sys 0m 11.89s | |root@OpenWrt:/mnt# time dd if=tempfile of=/dev/null bs=1M count=1024 |1024+0 records in |1024+0 records out |real 0m 8.41s |user 0m 0.01s |sys 0m 4.70s | |This means: 121 MB/s reading and 75 MB/s writing! | |The drive is a WD Green WD10EARX taken from an older MBL Single. |I repeated the test a few times with even larger files to rule out |any caching, I'm still seeing the same great performance. OpenWrt is |now completely on par with the original MBL firmware's performance. Another user And.short reported: |I can report that your fix worked! Boots up fine with two |drives even with more partitions, and no more reboot on |concurrent disk access! A closer look into the sata_dwc_460ex code revealed that the driver did initally set the correct protection control bits. However, this feature was lost when the sata_dwc_460ex driver was converted to the generic DMA driver framework. BugLink: https://forum.openwrt.org/t/wd-mybook-live-duo-two-disks/16195/55 BugLink: https://forum.openwrt.org/t/wd-mybook-live-duo-two-disks/16195/50 Fixes: 8b3444852a2b ("sata_dwc_460ex: move to generic DMA driver") Reviewed-by: Andy Shevchenko Signed-off-by: Christian Lamparter Signed-off-by: Vinod Koul

dmaengine: dw: add support of iDMA 32-bit hardware

2017-01-25T06:21:40Z

iDMA 32-bit is Intel designed DMA controller that behaves like Synopsys Designware DMA. This patch adds a support of the new Intel hardware. Due to iDMA 32-bit has no autoconfiguration the platform code must provide a platform data to dw_dma_probe(). By default full FIFO (1024 bytes) is assigned to channel 0. Here we slice FIFO on equal parts between channels for iDMA 32-bit case. Signed-off-by: Andy Shevchenko Signed-off-by: Vinod Koul

dmaengine: DW DMAC: add multi-block property to device tree

2016-11-30T03:27:50Z

Several versions of DW DMAC have multi block transfers hardware support. Hardware support of multi block transfers is disabled by default if we use DT to configure DMAC and software emulation of multi block transfers used instead. Add multi-block property, so it is possible to enable hardware multi block transfers (if present) via DT. Switch from per device is_nollp variable to multi_block array to be able enable/disable multi block transfers separately per channel. Acked-by: Andy Shevchenko Signed-off-by: Eugeniy Paltsev Signed-off-by: Vinod Koul

dmaengine: dw: override LLP support if asked in platform data

2016-08-31T14:13:29Z

There are at least two known devices, e.g. DMA controller found on ARC AXS101 SDP board, that have LLP register and no multi block transfer support at the same time. Override autodetection by user provided data. Reported-by: Eugeniy Paltsev Reviewed-by: Eugeniy Paltsev Signed-off-by: Andy Shevchenko Tested-by: Bryan O'Donoghue Signed-off-by: Greg Kroah-Hartman

dmaengine: dw: set polarity of handshake interface

2016-08-31T14:13:29Z

Intel Quark UART uses DesignWare DMA IP. Though the DMA IP is connected in such way that handshake interface uses inverted polarity. We have to provide a possibility to set this in the DMA driver when configuring a channel. Introduce a new member of custom slave configuration called 'hs_polarity' and set active low polarity in case this value is 'true'. Acked-by: Vinod Koul Signed-off-by: Andy Shevchenko Tested-by: Bryan O'Donoghue Signed-off-by: Greg Kroah-Hartman