dmaengine: stm32-mdma: correct desc prep when channel running

In case of the prep descriptor while the channel is already running, the
CCR register value stored into the channel could already have its EN bit
set.  This would lead to a bad transfer since, at start transfer time,
enabling the channel while other registers aren't yet properly set.
To avoid this, ensure to mask the CCR_EN bit when storing the ccr value
into the mdma channel structure.

Fixes: a4ffb13c8946 ("dmaengine: Add STM32 MDMA driver")
Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Cc: stable@vger.kernel.org
Tested-by: Alain Volmat <alain.volmat@foss.st.com>
Link: https://lore.kernel.org/r/20231009082450.452877-1-amelie.delaunay@foss.st.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/stm32-mdma.c b/drivers/dma/stm32-mdma.c
index 0c7d2295856e21a6c56047415dc2c0e61424f770..264abfb54a8e7e73a5ef50df61feb02b05879997 100644 (file)
--- a/drivers/dma/stm32-mdma.c
+++ b/drivers/dma/stm32-mdma.c
@@ -488,7 +488,7 @@ static int stm32_mdma_set_xfer_param(struct stm32_mdma_chan *chan,
        src_maxburst = chan->dma_config.src_maxburst;
        dst_maxburst = chan->dma_config.dst_maxburst;
 
-       ccr = stm32_mdma_read(dmadev, STM32_MDMA_CCR(chan->id));
+       ccr = stm32_mdma_read(dmadev, STM32_MDMA_CCR(chan->id)) & ~STM32_MDMA_CCR_EN;
        ctcr = stm32_mdma_read(dmadev, STM32_MDMA_CTCR(chan->id));
        ctbr = stm32_mdma_read(dmadev, STM32_MDMA_CTBR(chan->id));
 
@@ -966,7 +966,7 @@ stm32_mdma_prep_dma_memcpy(struct dma_chan *c, dma_addr_t dest, dma_addr_t src,
        if (!desc)
                return NULL;
 
-       ccr = stm32_mdma_read(dmadev, STM32_MDMA_CCR(chan->id));
+       ccr = stm32_mdma_read(dmadev, STM32_MDMA_CCR(chan->id)) & ~STM32_MDMA_CCR_EN;
        ctcr = stm32_mdma_read(dmadev, STM32_MDMA_CTCR(chan->id));
        ctbr = stm32_mdma_read(dmadev, STM32_MDMA_CTBR(chan->id));
        cbndtr = stm32_mdma_read(dmadev, STM32_MDMA_CBNDTR(chan->id));