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    SubjectRe: [PATCH v2 08/14] DMA: edma: Use different eventq for cyclic channels
    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@ti.com>
    >>> ---
    >>> 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


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