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+This document contains some hints to test the function of the VCHIQ driver
+without having additional hardware to the Raspberry Pi.
+
+* Requirements & limitations
+
+Testing the VCHIQ driver requires a Raspberry Pi with one of the following SoC:
+  - BCM2835 ( e.g. Raspberry Pi Zero W )
+  - BCM2836 ( e.g. Raspberry Pi 2 )
+  - BCM2837 ( e.g. Raspberry Pi 3 B+ )
+
+The BCM2711 used in the Raspberry Pi 4 is currently not supported in the
+mainline kernel.
+
+There are no specific requirements to the VideoCore firmware to get VCHIQ
+working.
+
+The test scenarios described in this document based on the tool vchiq_test.
+Its source code is available here: https://github.com/raspberrypi/userland
+
+* Configuration
+
+Here are the most common kernel configurations:
+
+ 1. BCM2835 target SoC (ARM 32 bit)
+
+    Just use bcm2835_defconfig which already has VCHIQ enabled.
+
+ 2. BCM2836/7 target SoC (ARM 32 bit)
+
+    Use the multi_v7_defconfig as a base and then enable all VCHIQ options.
+
+ 3. BCM2837 target SoC (ARM 64 bit)
+
+    Use the defconfig which has most of the VCHIQ options enabled.
+
+* Scenarios
+
+ * Initial test
+
+   Check the driver is probed and /dev/vchiq is created
+
+ * Functional test
+
+   Command: vchiq_test -f 10
+
+   Expected output:
+   Functional test - iters:10
+   ======== iteration 1 ========
+   Testing bulk transfer for alignment.
+   Testing bulk transfer at PAGE_SIZE.
+   ...
+
+ * Ping test
+
+   Command: vchiq_test -p
+
+   Expected output:
+   Ping test - service:echo, iters:1000, version 3
+   vchi ping (size 0) -> 57.000000us
+   vchi ping (size 0, 0 async, 0 oneway) -> 122.000000us
+   vchi bulk (size 0, 0 async, 0 oneway) -> 546.000000us
+   vchi bulk (size 0, 0 oneway) -> 230.000000us
+   vchi ping (size 0) -> 49.000000us
+   vchi ping (size 0, 0 async, 0 oneway) -> 70.000000us
+   vchi bulk (size 0, 0 async, 0 oneway) -> 296.000000us
+   vchi bulk (size 0, 0 oneway) -> 266.000000us
+   vchi ping (size 0, 1 async, 0 oneway) -> 65.000000us
+   vchi bulk (size 0, 0 oneway) -> 456.000000us
+   vchi ping (size 0, 2 async, 0 oneway) -> 74.000000us
+   vchi bulk (size 0, 0 oneway) -> 640.000000us
+   vchi ping (size 0, 10 async, 0 oneway) -> 125.000000us
+   vchi bulk (size 0, 0 oneway) -> 2309.000000us
+   vchi ping (size 0, 0 async, 1 oneway) -> 70.000000us
+   vchi ping (size 0, 0 async, 2 oneway) -> 76.000000us
+   vchi ping (size 0, 0 async, 10 oneway) -> 105.000000us
+   vchi ping (size 0, 10 async, 10 oneway) -> 165.000000us
+   vchi ping (size 0, 100 async, 0 oneway) -> nanus
+   vchi bulk (size 0, 0 oneway) -> nanus
+   vchi ping (size 0, 0 async, 100 oneway) -> nanus
+   vchi ping (size 0, 100 async, 100 oneway) -> infus
+   vchi ping (size 0, 200 async, 0 oneway) -> infus
+   ...
+
+ * Debugfs test
+
+   Command: cat /sys/kernel/debug/vchiq/state
+
+   Example output:
+   State 0: CONNECTED
+     tx_pos=0x1e8(@43b0acda), rx_pos=0x170(@05493af8)
+     Version: 8 (min 3)
+     Stats: ctrl_tx_count=7, ctrl_rx_count=7, error_count=0
+     Slots: 30 available (29 data), 0 recyclable, 0 stalls (0 data)
+     Platform: 2835 (VC master)
+     Local: slots 34-64 tx_pos=0x1e8 recycle=0x1f
+       Slots claimed:
+       DEBUG: SLOT_HANDLER_COUNT = 20(0x14)
+       DEBUG: SLOT_HANDLER_LINE = 1937(0x791)
+       DEBUG: PARSE_LINE = 1864(0x748)
+       DEBUG: PARSE_HEADER = -249155224(0xf1263168)
+       DEBUG: PARSE_MSGID = 67362817(0x403e001)
+       DEBUG: AWAIT_COMPLETION_LINE = 0(0x0)
+       DEBUG: DEQUEUE_MESSAGE_LINE = 0(0x0)
+       DEBUG: SERVICE_CALLBACK_LINE = 0(0x0)
+       DEBUG: MSG_QUEUE_FULL_COUNT = 0(0x0)
+       DEBUG: COMPLETION_QUEUE_FULL_COUNT = 0(0x0)
+     Remote: slots 2-32 tx_pos=0x170 recycle=0x1f
+       Slots claimed:
+         2: 10/9
+       DEBUG: SLOT_HANDLER_COUNT = 20(0x14)
+       DEBUG: SLOT_HANDLER_LINE = 1851(0x73b)
+       DEBUG: PARSE_LINE = 1827(0x723)
+       DEBUG: PARSE_HEADER = -150330912(0xf70a21e0)
+       DEBUG: PARSE_MSGID = 67113022(0x400103e)
+       DEBUG: AWAIT_COMPLETION_LINE = 0(0x0)
+       DEBUG: DEQUEUE_MESSAGE_LINE = 0(0x0)
+       DEBUG: SERVICE_CALLBACK_LINE = 0(0x0)
+       DEBUG: MSG_QUEUE_FULL_COUNT = 0(0x0)
+       DEBUG: COMPLETION_QUEUE_FULL_COUNT = 0(0x0)
+   Service 0: LISTENING (ref 1) 'PEEK little-endian (0x4b454550)' remote n/a (msg use 0/3840, slot use 0/15)
+     Bulk: tx_pending=0 (size 0), rx_pending=0 (size 0)
+     Ctrl: tx_count=0, tx_bytes=0, rx_count=0, rx_bytes=0
+     Bulk: tx_count=0, tx_bytes=0, rx_count=0, rx_bytes=0
+     0 quota stalls, 0 slot stalls, 0 bulk stalls, 0 aborted, 0 errors
+     instance b511f60b