On 04/11/2014 11:47 AM, Vinod Koul wrote: > On Thu, Apr 10, 2014 at 11:36:30AM -0500, Joel Fernandes wrote: >> On 04/01/2014 08:06 AM, Peter Ujfalusi wrote: >>> To improve latency with cyclic DMA operation it is preferred to >>> use different eventq/tc than the default which is used by all >>> other drivers (mmc, spi, i2c, etc). >>> When preparing the cyclic dma ask for non default queue for the >>> channel which is going to be used with cyclic mode. >>> >>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx> >>> --- >>> drivers/dma/edma.c | 3 +++ >>> 1 file changed, 3 insertions(+) >>> >>> diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c >>> index 1dd9e8806975..10048b40fac8 100644 >>> --- a/drivers/dma/edma.c >>> +++ b/drivers/dma/edma.c >>> @@ -628,6 +628,9 @@ static struct dma_async_tx_descriptor *edma_prep_dma_cyclic( >>> edesc->pset[i].opt |= TCINTEN; >>> } >>> >>> + /* Use different eventq/tc for cyclic DMA to reduce latency */ >>> + edma_request_non_default_queue(echan->ch_num); >>> + >>> return vchan_tx_prep(&echan->vchan, &edesc->vdesc, tx_flags); >>> } >>> >>> >> >> Is there any way to guarantee that the non-default queue is of the >> highest priority, or in other words default queue is of lowest priority. > well as we are discussing in other thread, it would make sense to pass the > required priority (i am using audio so pls give me highest one) > Yes, I'm aware of that part of the discussion ;) I also replied there. This post was sent much earlier on. thanks, -Joel -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
