Re: [PATCH v3 2/3] i2c: stm32f7: unmap DMA mapped buffer

[Clement LE GOFFIC]

Hi Andi,

On 7/2/25 19:08, Andi Shyti wrote:
> Hi Clement,
>
> On Mon, Jun 30, 2025 at 02:55:14PM +0200, Clément Le Goffic wrote:
> > Fix an issue where the mapped DMA buffer was not unmapped.
>
> "Fix an issue..." is too generic. Can you be more specific? Where
> was it mapped? Where was it left unmapped?
>
> Please, do consider that the user needs to understand what
> happens in the patch without needing to look into the patch.

Ok sure I'll refine the commit message.

> > Fixes: 7ecc8cfde553 ("i2c: i2c-stm32f7: Add DMA support")
> > Acked-by: Alain Volmat <alain.volmat@xxxxxxxxxxx>
> > Signed-off-by: Clément Le Goffic <clement.legoffic@xxxxxxxxxxx>
> > ---
> >   drivers/i2c/busses/i2c-stm32f7.c | 6 ++++++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
> > index e4aaeb2262d0..042386b4cabe 100644
> > --- a/drivers/i2c/busses/i2c-stm32f7.c
> > +++ b/drivers/i2c/busses/i2c-stm32f7.c
> > @@ -1554,6 +1554,8 @@ static irqreturn_t stm32f7_i2c_handle_isr_errs(struct stm32f7_i2c_dev *i2c_dev,
> >   	if (i2c_dev->use_dma) {
> >   		stm32f7_i2c_disable_dma_req(i2c_dev);
> >   		dmaengine_terminate_async(dma->chan_using);
> > +		dma_unmap_single(i2c_dev->dev, dma->dma_buf, dma->dma_len,
> > +				 dma->dma_data_dir);
> >   	}
> >   
> >   	i2c_dev->master_mode = false;
> > @@ -1622,6 +1624,8 @@ static irqreturn_t stm32f7_i2c_isr_event_thread(int irq, void *data)
> >   		if (i2c_dev->use_dma) {
> >   			stm32f7_i2c_disable_dma_req(i2c_dev);
> >   			dmaengine_terminate_async(dma->chan_using);
> > +			dma_unmap_single(i2c_dev->dev, dma->dma_buf, dma->dma_len,
> > +					 dma->dma_data_dir);
> >   		}
> >   		f7_msg->result = -ENXIO;
> >   	}
> > @@ -1642,6 +1646,8 @@ static irqreturn_t stm32f7_i2c_isr_event_thread(int irq, void *data)
> >   				dev_dbg(i2c_dev->dev, "<%s>: Timed out\n", __func__);
> >   				stm32f7_i2c_disable_dma_req(i2c_dev);
> >   				dmaengine_terminate_async(dma->chan_using);
> > +				dma_unmap_single(i2c_dev->dev, dma->dma_buf, dma->dma_len,
> > +						 dma->dma_data_dir);
>
> Can't we use the dma_callback here, or similar? I see some
> similar patterns and I think the code can be improved.

Yes, it seems the code can be factorized.
I'll submit a new version with the factorization.

Best regards,
Clément