2024-02-01 21:50:39

by Frank Li

Subject: [PATCH 1/1] dmaengine: fsl-qdma: fix SoC may hang on 16 byte unaligned read

From: Peng Ma <[email protected]>

There is chip (ls1028a) errata:

The SoC may hang on 16 byte unaligned read transactions by QDMA.

Unaligned read transactions initiated by QDMA may stall in the NOC
(Network On-Chip), causing a deadlock condition. Stalled transactions will
trigger completion timeouts in PCIe controller.

Workaround:
Enable prefetch by setting the source descriptor prefetchable bit
( SD[PF] = 1 ).

Implement this workaround.

Cc: [email protected]
Fixes: b092529e0aa0 ("dmaengine: fsl-qdma: Add qDMA controller driver for Layerscape SoCs")
Signed-off-by: Peng Ma <[email protected]>
Signed-off-by: Frank Li <[email protected]>
---
drivers/dma/fsl-qdma.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/fsl-qdma.c b/drivers/dma/fsl-qdma.c
index 47cb284680494..11d10dcd8b45d 100644
--- a/drivers/dma/fsl-qdma.c
+++ b/drivers/dma/fsl-qdma.c
@@ -109,6 +109,7 @@
#define FSL_QDMA_CMD_WTHROTL_OFFSET 20
#define FSL_QDMA_CMD_DSEN_OFFSET 19
#define FSL_QDMA_CMD_LWC_OFFSET 16
+#define FSL_QDMA_CMD_PF BIT(17)

/* Field definition for Descriptor status */
#define QDMA_CCDF_STATUS_RTE BIT(5)
@@ -384,7 +385,8 @@ static void fsl_qdma_comp_fill_memcpy(struct fsl_qdma_comp *fsl_comp,
qdma_csgf_set_f(csgf_dest, len);
/* Descriptor Buffer */
cmd = cpu_to_le32(FSL_QDMA_CMD_RWTTYPE <<
- FSL_QDMA_CMD_RWTTYPE_OFFSET);
+ FSL_QDMA_CMD_RWTTYPE_OFFSET) |
+ FSL_QDMA_CMD_PF;
sdf->data = QDMA_SDDF_CMD(cmd);

cmd = cpu_to_le32(FSL_QDMA_CMD_RWTTYPE <<
--
2.34.1

2024-02-07 08:56:52

by Vinod Koul

Subject: Re: [PATCH 1/1] dmaengine: fsl-qdma: fix SoC may hang on 16 byte unaligned read

On Thu, 01 Feb 2024 16:50:07 -0500, Frank Li wrote:
> There is chip (ls1028a) errata:
>
> The SoC may hang on 16 byte unaligned read transactions by QDMA.
>
> Unaligned read transactions initiated by QDMA may stall in the NOC
> (Network On-Chip), causing a deadlock condition. Stalled transactions will
> trigger completion timeouts in PCIe controller.
>
> [...]

Applied, thanks!

[1/1] dmaengine: fsl-qdma: fix SoC may hang on 16 byte unaligned read
commit: 9d739bccf261dd93ec1babf82f5c5d71dd4caa3e

Best regards,
--
~Vinod