From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Nikula Subject: Re: [PATCH 0/4] McBSP smart idle and DMA op mode updates for ASoC Date: Wed, 19 May 2010 08:13:25 +0300 Message-ID: <20100519081325.6e341075.jhnikula@gmail.com> References: <1274213594-26554-1-git-send-email-lrg@slimlogic.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1274213594-26554-1-git-send-email-lrg@slimlogic.co.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: Liam Girdwood Cc: Tony Lindgren , alsa-devel@alsa-project.org, linux-omap@vger.kernel.org, Peter Ujfalusi , Mark Brown List-Id: linux-omap@vger.kernel.org On Tue, 18 May 2010 21:13:10 +0100 Liam Girdwood wrote: > I've also added a patch to remove the mcbsp DMA op mode sysfs set functionality. > I think DMA op mode is very specific to the mcbsp client driver _only_ and > shouldn't really be changed by userspace. Please let me know if you use this > feature and I'll drop this patch. > I've used to say that the DMA op mode is more like use-case not machine specific but I'm not sure is my point valid onemore. I've used to think that low-latency processing would need accurate DMA pointer (op mode == element) while mp3 playback would need low power consumption (op mode == threshold). Peter: what's the status today how well can we do low-latency processing with threshold mode? IRCC, with your FIFO delay query patches, can we estimate the DMA pointer position with enough accuracy? -- Jarkko