New subject: 回复： [PATCH] ALSA: hda/via - fix occasionally no sound with VT1802

23 Nov 2021

      On Tue, 23 Nov 2021 09:07:14 +0100,
tianyucode wrote:
...
From: tianyu tianyu@kylinos.cn
Hi guys, I'm a new guy for audio driver.
I have encountered a problem. When using the VT1802 codec,
there will be no sound occasionally. After checking the initialization process,
I found that the cause of the problem is that the power state does not have
hda_set_power_state(codec, AC_PWRST_D0).

The power state is set to AC_PWRST_D0 during the first initialization：

azx_probe_continue
   azx_probe_codecs
   	snd_hda_codec_new
   		snd_hda_codec_device_new
   			hda_set_power_state(codec, AC_PWRST_D0);

Then, the power state is set to AC_PWRST_D3 in VT1802, but not set in realtek (ALC269).

azx_probe_continue
   azx_codec_configure
   	…
   	patch_vt2002
   		via_parse_auto_config
   			snd_hda_gen_parse_auto_config
   				add_all_pin_power_ctls
   					add_pin_power_ctls
   						set_path_power
static void add_all_pin_power_ctls(struct hda_codec *codec, bool on)
{
   /**/
   if (!codec->power_save_node)
   	return;
add_pin_power_ctls(codec, cfg->line_outs, cfg->line_out_pins, on);
   /**/
}
The power_save_node is set to 0 in patch_alc269 and it returns here,
but it is set to 1 in VT1802.
patch_vt2002P
   via_new_spec
   	codec->power_save_node = 1;
   via_parse_auto_config
   	snd_hda_gen_parse_auto_config
   	codec->power_save_node = 0;//it set to 0 here,but add_all_pin_power_ctls has been done
patch_alc269
   codec->power_save_node = 0;

Next there is a suspend and resume process, the resume process will also set the

power state to AC_PWRST_D0, but I think there is a problem with this process.
(1)suspend:
azx_probe_continue
   snd_card_register
   	..
   	snd_hda_codec_dev_register
   		snd_hda_codec_register
   			snd_hda_power_down
   				pm_runtime_put_autosuspend
   				__pm_runtime_suspend(dev, RPM_GET_PUT | RPM_ASYNC | RPM_AUTO);
   					rpm_suspend
static int rpm_suspend(struct device *dev, int rpmflags)
{
   /**/
   if (rpmflags & RPM_ASYNC) {
   	dev->power.request = (rpmflags & RPM_AUTO) ?
   	    RPM_REQ_AUTOSUSPEND : RPM_REQ_SUSPEND;
   	if (!dev->power.request_pending) {
   		dev->power.request_pending = true;
   		queue_work(pm_wq, &dev->power.work);
   	}
   	goto out;
   }
__update_runtime_status(dev, RPM_SUSPENDING);
/**/
   retval = rpm_callback(callback, dev);
   __update_runtime_status(dev, RPM_SUSPENDED);
   /**/
}
The first call to rpm_suspend has the RPM_ASYNC flag, so queue_work is called,
and the work queue is used to enter rpm_suspend
pm_runtime_init
   INIT_WORK(&dev->power.work, pm_runtime_work);
(2)resume:
azx_probe_continue
   set_default_power_save
   	snd_hda_set_power_save(&chip->bus, val * 1000);
   		codec_set_power_save(c, delay);
int val = power_save;
static int power_save = CONFIG_SND_HDA_POWER_SAVE_DEFAULT;//It is 0 in my .config
static void codec_set_power_save(struct hda_codec *codec, int delay)
{
   struct device *dev = hda_codec_dev(codec);
   if (delay == 0 && codec->auto_runtime_pm)
   	delay = 3000;
if (delay > 0) {
   	pm_runtime_set_autosuspend_delay(dev, delay);
   	pm_runtime_use_autosuspend(dev);
   	pm_runtime_allow(dev);
   	if (!pm_runtime_suspended(dev))
   		pm_runtime_mark_last_busy(dev);
   } else {
   	pm_runtime_dont_use_autosuspend(dev);
   	pm_runtime_forbid(dev);
   }
}
pm_runtime_forbid
   rpm_resume(dev, 0);
static int rpm_resume(struct device *dev, int rpmflags)
{
   /**/
   if (dev->power.runtime_status == RPM_ACTIVE) {
   	retval = 1;
   	goto out;
   }
/**/
   _update_runtime_status(dev, RPM_RESUMING);
   retval = rpm_callback(callback, dev);
   /**/
   __update_runtime_status(dev, RPM_ACTIVE);
   /**/
}
The callback functions of suspend and resume are as follows, which set the power state:
hda_call_codec_suspend
   state = hda_set_power_state(codec, AC_PWRST_D3);
hda_call_codec_resume
   hda_set_power_state(codec, AC_PWRST_D0);
You can see that the resume function relies on dev->power.runtime_status,
and the status is set in rpm_suspend. The operation of rpm_suspend depends
on the scheduling of the work queue. I added print debugging on my machine,
and occasionally there will be pm_runtime_work in Run after rpm_resume.
At this time, the suspend and resume processes are not performed correctly.
In VT1802, the power_state is still D3, and the machine has no sound.

I searched the Internet and did not find the relevant modification,

but found the commit 317d9313925c (ALSA: hda/realtek-Set default power save node to 0).
Does VIA need to be modified like this?
Since I am not familiar with ALSA and runtime pm, so come here to consult.
For VIA codecs, there is an additional fixup table to turn off the
power_save_node.  Add an entry with the PCI SSID of your device to
vt2002p_fixups[] table with VIA_FIXUP_POWER_SAVE.
thanks,
Takashi

Re: [PATCH] ALSA: hda/via - fix occasionally no sound with VT1802

Takashi Iwai

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