linux-kernel - Re: [PATCH 1/7] soundwire: bus: use sdw_update_no

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Date:   Mon, 7 Dec 2020 10:13:34 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     Bard Liao <yung-chuan.liao@...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, sanyog.r.kale@...el.com,
        rander.wang@...ux.intel.com, bard.liao@...el.com
Subject: Re: [PATCH 1/7] soundwire: bus: use sdw_update_no_pm when
 initializing a device

On 05-12-20, 08:59, Pierre-Louis Bossart wrote:
> Thanks for the review Vinod.
> 
> On 12/5/20 1:45 AM, Vinod Koul wrote:
> > On 03-12-20, 04:46, Bard Liao wrote:
> > > From: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> > > 
> > > When a Slave device is resumed, it may resume the bus and restart the
> > > enumeration. During that process, we absolutely don't want to call
> > > regular read/write routines which will wait for the resume to
> > > complete, otherwise a deadlock occurs.
> > > 
> > > Fixes: 60ee9be25571 ('soundwire: bus: add PM/no-PM versions of read/write functions')
> > 
> > Change looks okay, but not sure why this is a fix for adding no pm
> > version?
> 
> when we added the no_pm version, we missed the two cases below where
> sdw_update() was used and that creates a deadlock. To me that's a conceptual
> bug, we didn't fully use the no_pm versions, hence the Fixes tag.

Documentation says:
"A Fixes: tag indicates that the patch fixes an issue in a previous commit. It
is used to make it easy to determine where a bug originated, which can help
review a bug fix. This tag also assists the stable kernel team in determining
which stable kernel versions should receive your fix. This is the preferred
method for indicating a bug fixed by the patch. See :ref:`describe_changes`
for more details."

I do not this this helps here as this does not help distros etc
I would say this is incremental development which improved a case not
done properly earlier, unless you would like this to be backported.. In
that case it helps folks...

> It's ok to remove the tag if you don't think it's useful/relevant, what
> matters is that we agree on the content.

-- 
~Vinod