3.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Peter Ujfalusi <peter.ujfal...@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 <pme...@pmeerw.net>
Signed-off-by: Peter Ujfalusi <peter.ujfal...@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilim...@ti.com>
Acked-by: Russell King <rmk+ker...@arm.linux.org.uk>
Signed-off-by: Vinod Koul <vinod.k...@intel.com>
Signed-off-by: Greg Kroah-Hartman <gre...@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);
}
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
