[PATCH] dmaengine: dmatest: Don't forcibly terminate channel in polled mode

From: Nathan Lynch via B4 Relay
Date: Tue Apr 08 2025 - 09:39:12 EST


From: Nathan Lynch <nathan.lynch@xxxxxxx>

Invoking dmaengine_terminate_sync() against the channel after each
submitted descriptor is strange. It's benign when the test is
single-threaded, but disruptive when multiple threads are submitting
descriptors to the channel concurrently:

# cd /sys/module/dmatest/parameters/
# echo 1 > polled
# echo 2 > threads_per_chan
# echo dma0chan0 > channel
# echo 1 > run
...
dmatest: Added 2 threads using dma0chan0
dmatest: Started 2 threads using dma0chan0
xilinx-zynqmp-dma ffa80000.dma: dma_sync_wait: timeout!
xilinx-zynqmp-dma ffa80000.dma: dma_sync_wait: timeout!
dmatest: dma0chan0-copy0: result #3: 'test timed out' with
src_off=0x487 dst_off=0xf8 len=0x171b (0)
dmatest: dma0chan0-copy1: result #6: 'test timed out' with
src_off=0x227d dst_off=0xf99 len=0xf7a (0)

Remove the call to dmaengine_terminate_sync() from the main thread
loop.

Fixes: fb9816f9d05f ("dmaengine: dmatest: Add support for completion polling")
Signed-off-by: Nathan Lynch <nathan.lynch@xxxxxxx>
---
drivers/dma/dmatest.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index d891dfca358e209c9a5c2d8b49e3e539130e53e8..4e109c45fe0c5a7e8f337efe6e00e0616977f770 100644
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -835,7 +835,6 @@ static int dmatest_func(void *data)

if (params->polled) {
status = dma_sync_wait(chan, cookie);
- dmaengine_terminate_sync(chan);
if (status == DMA_COMPLETE)
done->done = true;
} else {

---
base-commit: 0af2f6be1b4281385b618cb86ad946eded089ac8
change-id: 20250403-dmaengine-dmatest-poll-mode-fix-671b02dc9084

Best regards,
--
Nathan Lynch <nathan.lynch@xxxxxxx>