2015-04-27 11:52:33

by John Ogness

Subject: [PATCH 2/3] dmaenegine: edma: allow pause/resume for non-cyclic mode

The 8250_omap serial driver relies on dmaengine_pause() actually
pausing the DMA transfer. Before this patch dmaengine_pause() is
a NOP for non-cylic DMA transfers. This allowed the 8250_omap
driver to read DMA buffers while the DMA was still active,
resulting in lost serial data.

Signed-off-by: John Ogness <[email protected]>
---
drivers/dma/edma.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index bf09db7..88853af 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -300,8 +300,7 @@ static int edma_dma_pause(struct dma_chan *chan)
{
struct edma_chan *echan = to_edma_chan(chan);

- /* Pause/Resume only allowed with cyclic mode */
- if (!echan->edesc || !echan->edesc->cyclic)
+ if (!echan->edesc)
return -EINVAL;

edma_pause(echan->ch_num);
@@ -312,10 +311,6 @@ static int edma_dma_resume(struct dma_chan *chan)
{
struct edma_chan *echan = to_edma_chan(chan);

- /* Pause/Resume only allowed with cyclic mode */
- if (!echan->edesc->cyclic)
- return -EINVAL;
-
edma_resume(echan->ch_num);
return 0;
}
--
1.7.10.4

2015-04-27 11:56:04

by Peter Ujfalusi

Subject: Re: [PATCH 2/3] dmaenegine: edma: allow pause/resume for non-cyclic mode

On 04/27/2015 02:52 PM, John Ogness wrote:
> The 8250_omap serial driver relies on dmaengine_pause() actually
> pausing the DMA transfer. Before this patch dmaengine_pause() is
> a NOP for non-cylic DMA transfers. This allowed the 8250_omap
> driver to read DMA buffers while the DMA was still active,
> resulting in lost serial data.

Acked-by: Peter Ujfalusi <[email protected]>

> Signed-off-by: John Ogness <[email protected]>
> ---
> drivers/dma/edma.c | 7 +------
> 1 file changed, 1 insertion(+), 6 deletions(-)
>
> diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
> index bf09db7..88853af 100644
> --- a/drivers/dma/edma.c
> +++ b/drivers/dma/edma.c
> @@ -300,8 +300,7 @@ static int edma_dma_pause(struct dma_chan *chan)
> {
> struct edma_chan *echan = to_edma_chan(chan);
>
> - /* Pause/Resume only allowed with cyclic mode */
> - if (!echan->edesc || !echan->edesc->cyclic)
> + if (!echan->edesc)
> return -EINVAL;
>
> edma_pause(echan->ch_num);
> @@ -312,10 +311,6 @@ static int edma_dma_resume(struct dma_chan *chan)
> {
> struct edma_chan *echan = to_edma_chan(chan);
>
> - /* Pause/Resume only allowed with cyclic mode */
> - if (!echan->edesc->cyclic)
> - return -EINVAL;
> -
> edma_resume(echan->ch_num);
> return 0;
> }
>


--
P?ter