Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030294AbaDJQg5 (ORCPT ); Thu, 10 Apr 2014 12:36:57 -0400 Received: from arroyo.ext.ti.com ([192.94.94.40]:45555 "EHLO arroyo.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933149AbaDJQgy (ORCPT ); Thu, 10 Apr 2014 12:36:54 -0400 Message-ID: <5346C88E.8010504@ti.com> Date: Thu, 10 Apr 2014 11:36:30 -0500 From: Joel Fernandes User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.1 MIME-Version: 1.0 To: Peter Ujfalusi , , , CC: , , , , , Subject: Re: [PATCH v2 08/14] DMA: edma: Use different eventq for cyclic channels References: <1396357575-30585-1-git-send-email-peter.ujfalusi@ti.com> <1396357575-30585-9-git-send-email-peter.ujfalusi@ti.com> In-Reply-To: <1396357575-30585-9-git-send-email-peter.ujfalusi@ti.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/01/2014 08:06 AM, Peter Ujfalusi wrote: > To improve latency with cyclic DMA operation it is preferred to > use different eventq/tc than the default which is used by all > other drivers (mmc, spi, i2c, etc). > When preparing the cyclic dma ask for non default queue for the > channel which is going to be used with cyclic mode. > > Signed-off-by: Peter Ujfalusi > --- > drivers/dma/edma.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c > index 1dd9e8806975..10048b40fac8 100644 > --- a/drivers/dma/edma.c > +++ b/drivers/dma/edma.c > @@ -628,6 +628,9 @@ static struct dma_async_tx_descriptor *edma_prep_dma_cyclic( > edesc->pset[i].opt |= TCINTEN; > } > > + /* Use different eventq/tc for cyclic DMA to reduce latency */ > + edma_request_non_default_queue(echan->ch_num); > + > return vchan_tx_prep(&echan->vchan, &edesc->vdesc, tx_flags); > } > > Is there any way to guarantee that the non-default queue is of the highest priority, or in other words default queue is of lowest priority. I know you set queue 1 as default because by default 0 is higher priority. And then assigning non-default queue. When assigning default to Queue 1, it would be good to also call assign_priority_to_queue and set QUEPRI to 7 for Queue 1. Since 0, 2 and 4 are all non-defaults. Thanks, -Joel -- 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/