On 12/6/20 10:43 PM, Vinod Koul wrote:
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@xxxxxxxxxxxxxxx>
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...
IMHO the changes in the series are absolutely required to have a
reliable suspend-resume operation and will need to be back-ported. When
I said 'conceptual bug', I didn't mean a hypothetical case, I really
meant that a proven race condition and timeouts will occur. That's not
good... We will provide the list of this patches to distros that are
known to support SoundWire as a 'must apply'.
If you look at the series, we provided Fixes tags for all patches except
'cosmetic' ones which don't fundamentally change the behavior (Patch 3,
patch 7) or when the code has not reached Linus' tree (patch 5).
That said, 5.10 was the first release where SoundWire started to be
functional so there's no need to apply these patches to earlier versions
of the stable tree.
Does this help?
