Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 08/27] dmaengine: omap-dma: Start DMA without delay for cyclic channels | Date | Sun, 14 Apr 2013 19:43:07 -0700 |
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3.8-stable review patch. If anyone has any objections, please let me know.
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From: Peter Ujfalusi <peter.ujfalusi@ti.com>
commit 765024697807ad1e1cac332aa891253ca4a339da upstream.
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 <pmeerw@pmeerw.net> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Vinod Koul <vinod.koul@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/dma/omap-dma.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-)
--- a/drivers/dma/omap-dma.c +++ b/drivers/dma/omap-dma.c @@ -276,12 +276,20 @@ static void omap_dma_issue_pending(struc 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); }
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