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

commit 03f25d53b145bc2f7ccc82fc04e4482ed734f524 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/dma/stm32-mdma.c b/drivers/dma/stm32-mdma.c
index 2e37c47044af52e3c523eb1c7b846d09dfae7451..5e17e2d3dccad359a24d29163f82056983f82e8f 100644 (file)
--- a/drivers/dma/stm32-mdma.c
+++ b/drivers/dma/stm32-mdma.c
@@ -490,7 +490,7 @@ 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));