linux-kernel - RE: [PATCH v2 3/5] ASoC: rt5640: Fix sleep in atomic context

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Message-ID: <953c899d04e543f681e44daad4ec2ff7@AcuMS.aculab.com>
Date:   Thu, 29 Jun 2023 10:21:06 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Mark Brown' <broonie@...nel.org>
CC:     'Sameer Pujar' <spujar@...dia.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzk+dt@...nel.org" <krzk+dt@...nel.org>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "perex@...ex.cz" <perex@...ex.cz>,
        "tiwai@...e.com" <tiwai@...e.com>,
        "jonathanh@...dia.com" <jonathanh@...dia.com>,
        "mkumard@...dia.com" <mkumard@...dia.com>,
        "sheetal@...dia.com" <sheetal@...dia.com>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Oder Chiou <oder_chiou@...ltek.com>
Subject: RE: [PATCH v2 3/5] ASoC: rt5640: Fix sleep in atomic context

From: Mark Brown
> Sent: 29 June 2023 11:11
> 
> On Thu, Jun 29, 2023 at 08:38:09AM +0000, David Laight wrote:
> > From: Sameer Pujar
> 
> > > Following prints are observed while testing audio on Jetson AGX Orin which
> > > has onboard RT5640 audio codec:
> > >
> > >   BUG: sleeping function called from invalid context at kernel/workqueue.c:3027
> > >   in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/0
> 
> > My 'gut feel' is that this will just move the problem elsewhere.
> 
> > If the ISR is responsible for adding audio buffers (etc) then it is
> > also not unlikely that the scheduling delays in running a threaded ISR
> > will cause audio glitches if the system is busy.
> 
> What makes you think this is anything to do with audio glitches?  The
> bug is literally what is described, it is not valid to sleep in atomic
> contexts and if we ever actually try things are likely to go badly.

What I mean is that deferring the ISR to process context
is likely to generate audio glitches on a busy system.

I realise that sleeping in an ISR goes badly wrong.

	David

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