[PATCH v2 1/4] dmaengine: xilinx: xdma: Fix the count of elapsed periods in cyclic mode

Miquel Raynal
2023-11-30T11:13:18Z

Xilinx DMA engine is capable of keeping track of the number of elapsed
periods and this is an increasing 32-bit counter which is only reset
when turning off the engine. No need to add this value to our local
counter.

Fixes: cd8c732ce1a5 ("dmaengine: xilinx: xdma: Support cyclic transfers")
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---

Hello, so far all my testing was performed by looping the playback
output to the recording input and comparing the files using
FFTs. Unfortunately, when the DMA engine suffers from the same issue on
both sides, some issues may appear un-noticed, which is likely what
happened here as the tooling did not report any issue while analyzing
the output until I actually listened to real audio now that I have in my
hands the relevant hardware/connectors to do so.
---
drivers/dma/xilinx/xdma.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/xilinx/xdma.c b/drivers/dma/xilinx/xdma.c
index 84a88029226f..2c9c72d4b5a2 100644
--- a/drivers/dma/xilinx/xdma.c
+++ b/drivers/dma/xilinx/xdma.c
@@ -754,9 +754,9 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
if (ret)
goto out;

- desc->completed_desc_num += complete_desc_num;
-
if (desc->cyclic) {
+ desc->completed_desc_num = complete_desc_num;
+
ret = regmap_read(xdev->rmap, xchan->base + XDMA_CHAN_STATUS,
&st);
if (ret)
@@ -768,6 +768,8 @@ static irqreturn_t xdma_channel_isr(int irq, void *dev_id)
goto out;
}

+ desc->completed_desc_num += complete_desc_num;
+
/*
* if all data blocks are transferred, remove and complete the request
*/
--
2.34.1