From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Nikula Subject: Re: [alsa-devel] [RFC PATCH 5/5] ASoC: omap-mcbsp: Place correct constraints for streams Date: Tue, 1 Jun 2010 14:20:47 +0300 Message-ID: <20100601142047.c6a549a8.jhnikula@gmail.com> References: <1275293810-31984-1-git-send-email-peter.ujfalusi@nokia.com> <201006011119.30651.peter.ujfalusi@nokia.com> <20100601122921.6d842ae8.jhnikula@gmail.com> <201006011330.11044.peter.ujfalusi@nokia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <201006011330.11044.peter.ujfalusi@nokia.com> Sender: linux-omap-owner@vger.kernel.org To: Peter Ujfalusi Cc: "alsa-devel@alsa-project.org" , "linux-omap@vger.kernel.org" , "tony@atomide.com" , "broonie@opensource.wolfsonmicro.com" , "Valentin Eduardo (Nokia-D/Helsinki)" , "Nurkkala Eero.An (EXT-Offcode/Oulu)" , Girdwood List-Id: alsa-devel@alsa-project.org On Tue, 1 Jun 2010 13:30:10 +0300 Peter Ujfalusi wrote: > Because, if you want to transfer in one SDMA burst more than the space free in > the McBSP FIFO, than where would the rest go? > I would have expected peripheral to deassert the DMA request but I haven't read the TRM so detail and experimenting with bigger period sizes didn't work so some /dev/null effect was obviously happening :-) > I guess it could be better than having 128 word long periods on McBSP1, 3, 4, > and 5. With small period size the applications also need to be woken up, but if > we silently handling the DMA IRQs, and the application is only woken up by every > 10. DMA IRQ, it might still save some power? > This is worth to experiment. Probably more interrupts with or without application wakeup reduction does not increase power as much as the savings are from core clocks being more idle. -- Jarkko