2023-10-09 08:25:58

by Amelie Delaunay

Subject: [PATCH] dmaengine: stm32-mdma: correct desc prep when channel running

From: Alain Volmat <[email protected]>

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 <[email protected]>
Signed-off-by: Amelie Delaunay <[email protected]>
Cc: [email protected]
---
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

2023-10-09 09:03:04

by Alain Volmat

Subject: Re: [PATCH] dmaengine: stm32-mdma: correct desc prep when channel running

Hi Am?lie,

thanks a lot.

Tested-by: Alain Volmat <[email protected]>

Regards,
Alain

On Mon, Oct 09, 2023 at 10:24:50AM +0200, Amelie Delaunay wrote:
> From: Alain Volmat <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Amelie Delaunay <[email protected]>
> Cc: [email protected]
> ---
> 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
>

2023-10-16 11:11:40

by Vinod Koul

Subject: Re: [PATCH] dmaengine: stm32-mdma: correct desc prep when channel running

On 09-10-23, 11:02, Alain Volmat wrote:
> Hi Am?lie,
>
> thanks a lot.
>
> Tested-by: Alain Volmat <[email protected]>

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

>
> Regards,
> Alain
>
> On Mon, Oct 09, 2023 at 10:24:50AM +0200, Amelie Delaunay wrote:
> > From: Alain Volmat <[email protected]>
> >
> > 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 <[email protected]>
> > Signed-off-by: Amelie Delaunay <[email protected]>
> > Cc: [email protected]
> > ---
> > 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

2023-10-16 11:13:26

by Vinod Koul

Subject: Re: [PATCH] dmaengine: stm32-mdma: correct desc prep when channel running

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,
--
~Vinod