linux-kernel - Re: [PATCH] sound: usb: pcm: fix incorrect power state when playing sound after PM

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Message-ID: <1591192216.23525.72.camel@mtkswgap22>
Date:   Wed, 3 Jun 2020 21:50:16 +0800
From:   Macpaul Lin <macpaul.lin@...iatek.com>
To:     Takashi Iwai <tiwai@...e.de>
CC:     <alsa-devel@...a-project.org>,
        Mediatek WSD Upstream <wsd_upstream@...iatek.com>,
        <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        Johan Hovold <johan@...nel.org>, Takashi Iwai <tiwai@...e.com>,
        Hui Wang <hui.wang@...onical.com>,
        Alexander Tsoy <alexander@...y.me>,
        <linux-mediatek@...ts.infradead.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Macpaul Lin <macpaul.lin@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Szabolcs Szőke <szszoke.code@...il.com>,
        <linux-arm-kernel@...ts.infradead.org>, <stable@...r.kernel.org>
Subject: Re: [PATCH] sound: usb: pcm: fix incorrect power state when playing
 sound after PM_AUTO suspend

On Wed, 2020-06-03 at 14:47 +0200, Takashi Iwai wrote:
> On Wed, 03 Jun 2020 14:39:24 +0200,
> Macpaul Lin wrote:
> > 
> > On Wed, 2020-06-03 at 10:45 +0200, Takashi Iwai wrote:
> > > On Wed, 03 Jun 2020 08:54:51 +0200,
> > > Takashi Iwai wrote:
> > > > 
> > > > On Wed, 03 Jun 2020 08:28:09 +0200,
> > > > Takashi Iwai wrote:
> > > > > 
> > > > > And, the most suspicious case is the last one,
> > > > > chip->num_suspended-intf.  It means that the device has multiple
> > > > > USB interfaces and they went to suspend, while the resume isn't
> > > > > performed for the all suspended interfaces in return.
> > > > 
> > > > If this is the cause, a patch like below might help.
> > > > It gets/puts the all assigned interfaced instead of only the primary
> > > > one.
> > > 
> > > ... and considering of the problem again, rather the patch below might
> > > be the right answer.  Now the driver tries to remember at which state
> > > it entered into the system-suspend.  Upon resume, in return, when the
> > > state reaches back to that point, set the card state to D0.
> > > 
> > > The previous patch can be applied on the top, too, and it might be
> > > worth to apply both.
> > > 
> > > Let me know if any of those actually helps.
> > > 
> > > 
> > > Takashi
> > 
> > Thanks for your response so quickly.
> > I've just test this patch since it looks like enough for the issue.
> 
> Good to hear!
> 
> > This patch worked since the flag system_suspend will be set at the same
> > time when power state has been changed. I have 2 interface with the head
> > set. But actually the problem happened when primary one is suspended.
> 
> Currently the autosuspend is set only to the primary interface; IOW,
> the other interfaces will never get autosuspend, and the another
> suspend-all-intf patch should improve that situation.  But it won't
> fix your actual bug, obviously :)
> 
> > So I didn't test the earlier patch "suspend all interface instead of
> > only the primary one."
> 
> Could you try it one on top of the last patch?  At least I'd like to
> see whether it causes any regression.

I've tried both of these 2 patches together, and it looks okay.

> > Will you resend this patch officially later? I think this solution is
> > required to send to stable, too. It's better to have it for other stable
> > kernel versions include android's.
> 
> Yes, that's a general bug and worth to be merged quickly.
> I'm going to submit a proper patch soon later.
> 
> 
> thanks,
> 
> Takashi
> 

Thanks!
Macpaul Lin