[PATCH 3/3] ARM: S3C64XX: Stop and flush requests on freeing
mcuelenaere at gmail.com
Sun Aug 15 09:42:28 EDT 2010
Op 15-08-10 15:36, Jassi Brar schreef:
> On Sun, Aug 15, 2010 at 10:28 PM, Jassi Brar <jassisinghbrar at gmail.com> wrote:
>> On Mon, May 31, 2010 at 8:34 PM, Maurus Cuelenaere
>> <mcuelenaere at gmail.com> wrote:
>>> When a DMA channel is freed, its pending requests should be flushed and the
>>> channel should be halted. This patch ensures that happens.
>>> Signed-off-by: Maurus Cuelenaere <mcuelenaere at gmail.com>
>>> arch/arm/mach-s3c64xx/dma.c | 3 ++-
>>> 1 files changed, 2 insertions(+), 1 deletions(-)
>>> diff --git a/arch/arm/mach-s3c64xx/dma.c b/arch/arm/mach-s3c64xx/dma.c
>>> index 1fd9d0c..e1f22af 100644
>>> --- a/arch/arm/mach-s3c64xx/dma.c
>>> +++ b/arch/arm/mach-s3c64xx/dma.c
>>> @@ -560,7 +560,8 @@ int s3c2410_dma_free(unsigned int channel, struct s3c2410_dma_client *client)
>>> channel, chan->client, client);
>>> - /* sort out stopping and freeing the channel */
>>> + s3c64xx_dma_flush(chan);
>>> + s3c64xx_dma_stop(chan);
>> I think, the order should be reverted.
You're probably right.
> Though it's a matter of S3C DMA API spec.
> Shouldn't the client be made to explicitly do S3C2410_DMAOP_FLUSH
> a pending req before freeing the channel? If so, the patch may not be needed.
I can't find anything about the client needing to flush the request itself.
Documentation/arm/Samsung-S3C24XX/DMA.txt doesn't mention anything regarding it
and the comment above s3c2410_dma_free() says "release the given channel back to
the system, will stop and flush any outstanding transfers, and ensure the
channel is ready for the next claimant."
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