Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933148Ab3DOCnn (ORCPT ); Sun, 14 Apr 2013 22:43:43 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:36462 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756972Ab3DOCni (ORCPT ); Sun, 14 Apr 2013 22:43:38 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Peter Meerwald , Peter Ujfalusi , Santosh Shilimkar , Russell King , Vinod Koul Subject: [ 08/27] dmaengine: omap-dma: Start DMA without delay for cyclic channels Date: Sun, 14 Apr 2013 19:43:07 -0700 Message-Id: <20130415024231.986725437@linuxfoundation.org> X-Mailer: git-send-email 1.8.2.1.368.g99c2266 In-Reply-To: <20130415024231.351969241@linuxfoundation.org> References: <20130415024231.351969241@linuxfoundation.org> User-Agent: quilt/0.60-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1957 Lines: 60 3.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Ujfalusi 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 Signed-off-by: Peter Ujfalusi Acked-by: Santosh Shilimkar Acked-by: Russell King Signed-off-by: Vinod Koul Signed-off-by: Greg Kroah-Hartman --- 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 majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/