Re: [PATCH] sound: usb: pcm: fix incorrect power state when playing sound after PM_AUTO suspend

From: Macpaul Lin <macpaul.lin@mediatek.com>
To: Takashi Iwai <tiwai@suse.de>
Cc: alsa-devel@alsa-project.org,
	"Szabolcs Szőke" <szszoke.code@gmail.com>,
	"Mediatek WSD Upstream" <wsd_upstream@mediatek.com>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	linux-usb@vger.kernel.org, "Takashi Iwai" <tiwai@suse.com>,
	stable@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Hui Wang" <hui.wang@canonical.com>,
	"Alexander Tsoy" <alexander@tsoy.me>,
	linux-mediatek@lists.infradead.org,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	"Johan Hovold" <johan@kernel.org>,
	"Jaroslav Kysela" <perex@perex.cz>,
	"Macpaul Lin" <macpaul.lin@gmail.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] sound: usb: pcm: fix incorrect power state when playing sound after PM_AUTO suspend
Date: Wed, 3 Jun 2020 21:50:16 +0800	[thread overview]
Message-ID: <1591192216.23525.72.camel@mtkswgap22> (raw)
In-Reply-To: <s5hr1uwco4c.wl-tiwai@suse.de>

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
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