linux-kernel - Re: [PATCH] ALSA: hda: fix snd_hda_bus_reset when single

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Message-ID: <87o75e340p.wl-tiwai@suse.de>
Date: Tue, 27 Aug 2024 07:53:42 +0200
From: Takashi Iwai <tiwai@...e.de>
To: soxiebing <soxiebing@....com>
Cc: tiwai@...e.de,
	linux-sound@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ALSA: hda: fix snd_hda_bus_reset when single_cmd is not supported

On Tue, 27 Aug 2024 05:30:43 +0200,
soxiebing wrote:
> 
> >On Mon, 26 Aug 2024 11:19:58 +0200,
> >soxiebing wrote:
> >> 
> >> >On Wed, 21 Aug 2024 03:42:38 +0200,
> >> >soxiebing wrote:
> >> >> 
> >> >> From: songxiebing <songxiebing@...inos.cn>
> >> >> 
> >> >> When an azx_get_desponse timeout occurs, ensure that bus_reset
> >> >> can be used when fallback_to_single_cmd is not supported.
> >> >> 
> >> >> Signed-off-by: songxiebing <songxiebing@...inos.cn>
> >> >
> >> >Why do you need to change?  Does it fix any real problem you faced?
> >> 
> >> Thanks for reply, i am testing all these days, but the problem is
> >> still exists even if using bus reset.
> >>
> >> The problem i encountered is that hda_call_codec_resume returned 
> >> timeout of 120 seconds(defined CONFIG_DPM_WATCHDOG)) when doing s4, 
> >> azx_get_response timeout occured, it is a low probability event.
> >> 
> >> To avoid exceeding 120s, can i change the count value to 3 in 
> >> hda_set_power_state ?
> >
> >So the change you suggested isn't for any real "fix" but to allow the
> >possible workaround with single_cmd to be applicable somehow in a
> >different form.  Then we should rather try debugging the original
> >issue, instead of change it.
> >
> >Does the response timeout happen *during* the S4 suspend, or during S4
> >resume, or after S4 resume?
> >
> >To be noted, the behavior you changed is only for the single_cmd
> >option is set explicitly, so it's more or less the designed behavior,
> >and I don't think it's good to change blindly.
> 
> The timeout happen during S4 resume. 
> 
> In hda_set_power_state function, the count value setting at most 10 times,
> i feel like there are a lot of retries, can we change it to 3 times, to avoid
> exceeding 120s ?

No, no, if such a long timeout happens, something is already wrong.
Extending it is no real fix at all.

You need to figure out which access or action causes the problem at
first.


Takashi