From 765024697807ad1e1cac332aa891253ca4a339da Mon Sep 17 00:00:00 2001 From: Peter Ujfalusi Date: Tue, 9 Apr 2013 16:33:06 +0200 Subject: [PATCH] dmaengine: omap-dma: Start DMA without delay for cyclic channels cyclic DMA is only used by audio which needs DMA to be started without a delay. If the DMA for audio is started using the tasklet we experience random channel switch (to be more precise: channel shift). Reported-by: Peter Meerwald CC: stable@vger.kernel.org # v3.7+ Signed-off-by: Peter Ujfalusi Acked-by: Santosh Shilimkar Acked-by: Russell King Signed-off-by: Vinod Koul --- drivers/dma/omap-dma.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) diff --git a/drivers/dma/omap-dma.c b/drivers/dma/omap-dma.c index c4b4fd2acc42..08b43bf37158 100644 --- a/drivers/dma/omap-dma.c +++ b/drivers/dma/omap-dma.c @@ -276,12 +276,20 @@ static void omap_dma_issue_pending(struct dma_chan *chan) spin_lock_irqsave(&c->vc.lock, flags); if (vchan_issue_pending(&c->vc) && !c->desc) { - struct omap_dmadev *d = to_omap_dma_dev(chan->device); - spin_lock(&d->lock); - if (list_empty(&c->node)) - list_add_tail(&c->node, &d->pending); - spin_unlock(&d->lock); - tasklet_schedule(&d->task); + /* + * c->cyclic is used only by audio and in this case the DMA need + * to be started without delay. + */ + if (!c->cyclic) { + struct omap_dmadev *d = to_omap_dma_dev(chan->device); + spin_lock(&d->lock); + if (list_empty(&c->node)) + list_add_tail(&c->node, &d->pending); + spin_unlock(&d->lock); + tasklet_schedule(&d->task); + } else { + omap_dma_start_desc(c); + } } spin_unlock_irqrestore(&c->vc.lock, flags); } -- GitLab