Hi Takashi,
-----Original Message----- From: Takashi Iwai [mailto:tiwai@suse.de] Sent: Tuesday, March 26, 2019 4:54 PM To: Yang, Libin libin.yang@intel.com Cc: alsa-devel@alsa-project.org; broonie@kernel.org Subject: Re: [alsa-devel] [PATCH V2] ASoC: fix hdmi codec driver contest in S3
On Tue, 26 Mar 2019 09:46:31 +0100, Yang, Libin wrote:
Hi Takashi
In the case of legacy HD-audio, we "fixed" the problem by avoiding the trigger of async work at resume, but let it be triggered from runtime resume. In ASoC case, however, it's no option.
Maybe a possible solution in the sound driver side would be to move from system suspend/resume to ASoC component suspend/resume. The runtime suspend/resume can be kept as is, and call pm_runtime_force_suspend and resume from the component
suspend/resume
callbacks. Since the component callbacks are certainly processed before DAPM events, this should assure the order.
I tried to move display power setting from runtime suspend/resume to component suspend/resume. I found there may be another issue: playback will NOT call component suspend/resume. This means we will never have chance to set the display power if we don't do the S3.
The runtime suspend/resume are fine and need to be kept, I suppose. The only problem is the system suspend/resume callbacks that call pm_runtime_force_*(). Just moving these two to component would work?
Let's see the flow of the suspend: 1. Component suspend is called. It will call snd_hdac_display_power() to turn off the display power. 2. runtime suspend is called. It will operate on the registers. This is wrong. We can't operate on registers when the power is off.
So I think we can only call snd_hdac_display_power() either in component suspend/resume or runtime suspend/resume. We can't call snd_hdac_display_power() in both.
And based on the previous test, component suspend/resume will not be called when playback. So we can only call snd_hdac_display_power() in runtime suspend/resume?
Regards, Libin
Takashi