On Wed, 11 Nov 2015 15:53:05 +0100, Yang, Libin wrote: > > > > > -----Original Message----- > > From: Takashi Iwai [mailto:tiwai@xxxxxxx] > > Sent: Wednesday, November 11, 2015 10:42 PM > > To: Yang, Libin > > Cc: libin.yang@xxxxxxxxxxxxxxx; David Henningsson; alsa-devel@alsa- > > project.org; mengdong.lin@xxxxxxxxxxxxxxx > > Subject: Re: [PATCH] ALSA - hda: hdmi flag to stop playback when > > monitor is disconnected > > > > On Wed, 11 Nov 2015 15:23:42 +0100, > > Yang, Libin wrote: > > > > > > > > > > -----Original Message----- > > > > From: Takashi Iwai [mailto:tiwai@xxxxxxx] > > > > Sent: Wednesday, November 11, 2015 10:13 PM > > > > To: libin.yang@xxxxxxxxxxxxxxx > > > > Cc: David Henningsson; alsa-devel@xxxxxxxxxxxxxxxx; > > > > mengdong.lin@xxxxxxxxxxxxxxx; Yang, Libin > > > > Subject: Re: [PATCH] ALSA - hda: hdmi flag to stop playback when > > > > monitor is disconnected > > > > > > > > On Wed, 11 Nov 2015 10:02:14 +0100, > > > > Takashi Iwai wrote: > > > > > > > > > > On Wed, 11 Nov 2015 09:39:09 +0100, > > > > > libin.yang@xxxxxxxxxxxxxxx wrote: > > > > > > > > > > > > From: Libin Yang <libin.yang@xxxxxxxxxxxxxxx> > > > > > > > > > > > > Add a flag that user can decide to stop HDMI/DP playback when > > > > > > the corresponding monitor is disconnected and refuse to open > > PCM > > > > > > if there is no monitor connected. > > > > > > > > > > > > Background: > > > > > > When a monitor is disconnected and a new monitor is connected, > > > > > > the parameters of the 2 monitors may be different. Audio driver > > > > > > need handle this situation. > > > > > > > > > > > > Besides, stopping playback when monitor is disconnected will > > > > > > help to save the power. > > > > > > > > > > > > Signed-off-by: Libin Yang <libin.yang@xxxxxxxxxxxxxxx> > > > > > > > > > > Thanks. Below are just nitpicking, so let's test this patch at first, > > > > > especially to see whether it has any significant influence on PA, then > > > > > respin with the fixes. > > > > > > > > > > David, care to check in your side, too? > > > > > > > > So I tested this with PA 7.1, and it failed, unfortunately. > > > > In short: > > > > - PA needs the PCM access at probe. If it gets an error, the device > > > > will be never enumerated again > > > > > > Thanks for test. > > > > > > If so, should we re-write the hdmi_pcm_open() and > > > generic_hdmi_playback_pcm_prepare() function to make > > > the probe works? Or not support dynamic pcm assignment? > > > > > > > - PA removes the device when it's disconnected. The PCM stop with > > > > DISCONNECT state leads to the device disappearance. > > > > > > If we can't use DISCONNECT, what else can we use? Or we can't > > > stop PCM when monitor is disconnected? > > > > One obvious options is: we don't care about it. Maybe care it only > > when really needed, e.g. return an error only in prepare and cleanup, > > but not in open. > > Get it. I will refine the patch. > > So we will not care the disconnect when playback and > not stop the PCM? > > If we don't stop pcm, how to handle connect a different monitor? > It seems userspace must handle such scenario. Yes. The driver just wishes that user-space reacts. Of course, you can do more complex. It's only the question about user-space interface, so you can actually stop the stream but makes it appearing as if a normal error to user-space. But I don't think it's worth to play with. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
