Messages in this thread | | | Date | Fri, 11 Apr 2014 15:51:43 -0500 | From | Joel Fernandes <> | Subject | Re: [PATCH v2 03/14] dma: edma: Add support for DMA_PAUSE/RESUME operation |
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On 04/11/2014 11:43 AM, Vinod Koul wrote: > On Tue, Apr 01, 2014 at 04:06:04PM +0300, Peter Ujfalusi wrote: >> Pause/Resume can be used by the audio stack when the stream is paused/resumed >> The edma platform code has support for this and the legacy audio stack used >> this. >> >> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> >> --- >> drivers/dma/edma.c | 28 ++++++++++++++++++++++++++++ >> 1 file changed, 28 insertions(+) >> >> diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c >> index 2742867fd1e6..7891378a03f0 100644 >> --- a/drivers/dma/edma.c >> +++ b/drivers/dma/edma.c >> @@ -240,6 +240,26 @@ static int edma_slave_config(struct edma_chan *echan, >> return 0; >> } >> >> +static int edma_dma_pause(struct edma_chan *echan) >> +{ >> + /* Pause/Resume only allowed with cyclic mode */ >> + if (!echan->edesc->cyclic) >> + return -EINVAL; > why this artificial restriction? The driver can do pause even for non cyclic > cases too? Yes the usage is in cyclic context but why should we limit any future > work on this? >
We struggled with this, and we certainly we don't want pauses in non-cyclic EDMA... we tried doing a "pause" and it was a disaster as the events keep coming in and those can't be paused, and EDMA hardware wont queue them during the pause, it'll just generate an error interrupt storm.
Thanks, -Joel
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