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From: Ladislav Michl <ladis@linux-mips.org>
To: Tomas Novotny <tomas@novotny.cz>
Cc: alsa-devel@alsa-project.org, linux-omap@vger.kernel.org
Subject: Re: omap-mcbsp: TX Buffer Overflow
Date: Sat, 7 Sep 2019 11:13:58 +0200	[thread overview]
Message-ID: <20190907091358.GA7166@lenoch> (raw)
In-Reply-To: <20190906165109.53c5a306@tomas.local.tbs-biometrics.cz>

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

  reply	other threads:[~2019-09-07  9:13 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-06 14:51 omap-mcbsp: TX Buffer Overflow Tomas Novotny
2019-09-07  9:13 ` Ladislav Michl [this message]
2019-09-09 16:24   ` Tony Lindgren
2019-09-10  8:05     ` Tomas Novotny

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