linux-kernel - Re: [PATCH] soundwire: cadence: fix race condition between suspend and Slave device alerts

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Date:   Wed, 9 Sep 2020 13:29:22 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Jaroslav Kysela <perex@...ex.cz>
Cc:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        alsa-devel@...a-project.org, tiwai@...e.de,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        ranjani.sridharan@...ux.intel.com, hui.wang@...onical.com,
        broonie@...nel.org, srinivas.kandagatla@...aro.org,
        jank@...ence.com, mengdong.lin@...el.com, sanyog.r.kale@...el.com,
        Bard Liao <yung-chuan.liao@...ux.intel.com>,
        rander.wang@...ux.intel.com, bard.liao@...el.com
Subject: Re: [PATCH] soundwire: cadence: fix race condition between suspend
 and Slave device alerts

On 08-09-20, 13:58, Jaroslav Kysela wrote:
> Dne 28. 08. 20 v 17:14 Pierre-Louis Bossart napsal(a):
> > 
> > 
> > 
> >> Is this timeout for suspend or resume? Somehow I was under the
> >> assumption that it is former? Or is the result seen on resume?
> >>
> >> Rereading the race describe above in steps, I think this should be
> >> handled in step c above. Btw is that suspend or runtime suspend which
> >> causes this? Former would be bigger issue as we should not have work
> >> running when we return from suspend call. Latter should be dealt with
> >> anyway as device might be off after suspend.
> > 
> > This happens with a system suspend. Because we disable the interrupts, 
> > the workqueue never completes, and we have a timeout on system resume.
> > 
> > That's why we want to prevent the workqueue from starting, or let it 
> > complete, but not have this zombie state where we suspend but there's 
> > still a wait for completion that times out later. The point here is 
> > really  making sure the workqueue is not used before suspend.
> > 
> 
> Vinod, there is no acceptance progress on this. The patch is really straight
> and for the Intel controller. They know what they're doing. I would apply
> this. The code can be refined at anytime. It's a fix. I tested it and I can
> confirm, that it fixes the issue. It's a vital patch for 5.10 to enable
> finally SoundWire drivers for the Intel hardware.

I do feel that there is something else going on, but not able to pin
point, anyway this fixes the issue so I am applying it now
> 
> Acked-by: Jaroslav Kysela <perex@...ex.cz>

Thanks for ack

-- 
~Vinod