From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ladislav Michl Subject: Re: omap-mcbsp: TX Buffer Overflow Date: Sat, 7 Sep 2019 11:13:58 +0200 Message-ID: <20190907091358.GA7166@lenoch> References: <20190906165109.53c5a306@tomas.local.tbs-biometrics.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20190906165109.53c5a306@tomas.local.tbs-biometrics.cz> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" To: Tomas Novotny Cc: alsa-devel@alsa-project.org, linux-omap@vger.kernel.org List-Id: linux-omap@vger.kernel.org On Fri, Sep 06, 2019 at 04:51:09PM +0200, Tomas Novotny wrote: > Hi, > > we have AM3703 based board similar to BeagleBoard. I'm hitting this error > after upgrade to latest LTS 4.19.71 (upgraded from 4.1): > > omap-mcbsp 49022000.mcbsp: TX Buffer Overflow! > > This appears during or after playing of short (~2s) ding-dong wav. That error > exists for longer time, because handling of tx buffer overflow irq was > introduced in 2016: 4e85e7776eba ("ASoC: omap-mcbsp: Enable TX/RX under and > overflow interrupts"). I've cherry-picked it to 4.1 and I see the error there also. > The sound seems clear and ok to me, but we are using low quality speaker. Just FYI, for stream capture there's omap-mcbsp 49022000.mcbsp: RX Buffer Underflow! As far as I remember all stable kernels we have in production - 4.9.x, 4.14.x and 4.19.x - are affected. IGEPv2 with both DM3730 and OMAP3530 are affected (headless machines, CONFIG_VIDEO_OMAP3=n). And DT is probably worth updating: omap_hwmod: mcbsp2_sidetone using broken dt data from mcbsp omap_hwmod: mcbsp3_sidetone using broken dt data from mcbsp I never motivated myself to dig deeper as catured stream looks pretty normal. l. > There are two workarounds to get rid of the message: > 1) Change 'dma_op_mode' sysfs attribute from 'element' to 'threshold'. I > found that just by coincidence when checking sysfs attributes. > 2) Compile kernel with CONFIG_VIDEO_OMAP3=y. Found on Logic PD forum [1]. > > Does anybody have any idea what's going wrong? Or why these (somehow) > unrelated workarounds help? > > Thanks, > > Tomas > > [1] https://support.logicpd.com/TDGForum/tabid/124/aft/2277/Default.aspx