Commit 76502469 authored Apr 09, 2013 by Peter Ujfalusi Committed by Vinod Koul Apr 10, 2013

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 <pmeerw@pmeerw.net>
CC: stable@vger.kernel.org  # v3.7+
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>

parent 0b94c577

drivers/dma/omap-dma.c

+14 −6

Original line number	Diff line number	Diff line
		@@ -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) {
		/*
		* 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);
		}