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

Message ID 20231009082450.452877-1-amelie.delaunay@foss.st.com
State New
Headers
Series dmaengine: stm32-mdma: correct desc prep when channel running |

Commit Message

Amelie Delaunay Oct. 9, 2023, 8:24 a.m. UTC
  From: Alain Volmat <alain.volmat@foss.st.com>

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
---
 drivers/dma/stm32-mdma.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
  

Comments

Alain Volmat Oct. 9, 2023, 9:02 a.m. UTC | #1
Hi Amélie,

thanks a lot.

Tested-by: Alain Volmat <alain.volmat@foss.st.com>

Regards,
Alain

On Mon, Oct 09, 2023 at 10:24:50AM +0200, Amelie Delaunay wrote:
> From: Alain Volmat <alain.volmat@foss.st.com>
> 
> 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
> ---
>  drivers/dma/stm32-mdma.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma/stm32-mdma.c b/drivers/dma/stm32-mdma.c
> index bae08b3f55c7..f414efdbd809 100644
> --- a/drivers/dma/stm32-mdma.c
> +++ b/drivers/dma/stm32-mdma.c
> @@ -489,7 +489,7 @@ 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));
>  
> @@ -965,7 +965,7 @@ 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));
> -- 
> 2.25.1
>
  
Vinod Koul Oct. 16, 2023, 11:11 a.m. UTC | #2
On 09-10-23, 11:02, Alain Volmat wrote:
> Hi Amélie,
> 
> thanks a lot.
> 
> Tested-by: Alain Volmat <alain.volmat@foss.st.com>

Please **do ** not ** top post!

> 
> Regards,
> Alain
> 
> On Mon, Oct 09, 2023 at 10:24:50AM +0200, Amelie Delaunay wrote:
> > From: Alain Volmat <alain.volmat@foss.st.com>
> > 
> > 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
> > ---
> >  drivers/dma/stm32-mdma.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/dma/stm32-mdma.c b/drivers/dma/stm32-mdma.c
> > index bae08b3f55c7..f414efdbd809 100644
> > --- a/drivers/dma/stm32-mdma.c
> > +++ b/drivers/dma/stm32-mdma.c
> > @@ -489,7 +489,7 @@ 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));
> >  
> > @@ -965,7 +965,7 @@ 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));
> > -- 
> > 2.25.1
> >
  
Vinod Koul Oct. 16, 2023, 11:13 a.m. UTC | #3
On Mon, 09 Oct 2023 10:24:50 +0200, Amelie Delaunay wrote:
> 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.
> 
> [...]

Applied, thanks!

[1/1] dmaengine: stm32-mdma: correct desc prep when channel running
      commit: 03f25d53b145bc2f7ccc82fc04e4482ed734f524

Best regards,
  

Patch

diff --git a/drivers/dma/stm32-mdma.c b/drivers/dma/stm32-mdma.c
index bae08b3f55c7..f414efdbd809 100644
--- a/drivers/dma/stm32-mdma.c
+++ b/drivers/dma/stm32-mdma.c
@@ -489,7 +489,7 @@  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));
 
@@ -965,7 +965,7 @@  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));