Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765547Ab3DJFdv (ORCPT ); Wed, 10 Apr 2013 01:33:51 -0400 Received: from mga14.intel.com ([143.182.124.37]:6972 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756157Ab3DJFdu (ORCPT ); Wed, 10 Apr 2013 01:33:50 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,444,1363158000"; d="scan'208";a="225374759" Date: Wed, 10 Apr 2013 10:34:41 +0530 From: Vinod Koul To: Peter Ujfalusi Cc: Russell King - ARM Linux , Dan Williams , Tony Lindgren , Jarkko Nikula , Santosh Shilimkar , Felipe Balbi , linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Peter Meerwald , patches@linaro.org, stable@vger.kernel.org.#.v3.7+ Subject: Re: [PATCH] dmaengine: omap-dma: Start DMA without delay for cyclic channels Message-ID: <20130410050441.GJ31193@intel.com> References: <1365517986-9401-1-git-send-email-peter.ujfalusi@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1365517986-9401-1-git-send-email-peter.ujfalusi@ti.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2389 Lines: 71 On Tue, Apr 09, 2013 at 04:33:06PM +0200, Peter Ujfalusi wrote: > 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 > --- > Hi Vinod, > > Would it be possible to send this patch for 3.9. The channel shift (or switch) > issue in audio has been noticed recently and it turns out that it has been > present since 3.7 kernel. > It would be great if 3.9 kernel could work correctly out of box... Applied to fixes. I will send this to linus in a day... -- ~Vinod > > Changes since RFCv2: > - added Acked-by from Santosh and Russell > > Thank you, > Peter > > 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 2ea3d7e..ec3fc4f 100644 > --- a/drivers/dma/omap-dma.c > +++ b/drivers/dma/omap-dma.c > @@ -282,12 +282,20 @@ 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); > } > -- > 1.8.1.5 > -- 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/