On Mon, 06 May 2019 17:47:25 +0200, Pierre-Louis Bossart wrote: > > On 5/6/19 10:41 AM, Takashi Iwai wrote: > > On Mon, 06 May 2019 17:37:32 +0200, > > Pierre-Louis Bossart wrote: > >> > >> On 5/6/19 1:59 AM, libin.yang@xxxxxxxxx wrote: > >>> From: Libin Yang <libin.yang@xxxxxxxxx> > >>> > >>> This patch move the check of monitor from hw_params to trigger callback. > >>> > >>> The original code will check the monitor presence in hw_params. If the > >>> monitor doesn't exist, hw_params will return -ENODEV. Mostly this is OK. > >>> > >>> However, pulseaudio will check the pcm devices when kernel is booting up. > >>> It will try to open, set hw_params, prepare such pcm devices. We can't > >>> guarantee that the monitor will be connected when kernel is booting up. > >>> Especially, hdac_hdmi will export 3 pcms at most. It's hard to say users > >>> will connect 3 monitors to the HDMI/DP ports. This will cause pulseaudio > >>> fail in parsing the pcm devices because the driver will return -ENODEV in > >>> hw_params. > >>> > >>> This patch tries to move the check of monitor presence into trigger > >>> callback. This can "trick" the pulseaudio the pcm is ready. > >>> > >>> This bug is found when we try to enable HDMI detection in > >>> gnome-sound-setting for ASoC hdac_hdmi. After we enable the hdmi in UCM, > >>> pulseaudio will try to parse the hdmi pcm devices. It will cause failure if > >>> there are no monitors connected. > >> > >> Out of curiosity, how is this handled in the legacy driver? I haven't > >> done this for a long time but I remember very clearly being able to > >> play on the HDMI:3,7, etc devices without any monitors > >> connected. You'd get of course no sound but there was no error > >> reported to userspace. The hardware is perfectly capable of pushing > >> samples into the display controller using the HDAudio/iDisp link. > > > > As mentioned in the thread, PA just picks up the stream that is > > connected via a monitor by checking / notified by the corresponding > > Jack control. On hdac_hdmi driver, the jack control has different > > base name that is irrelevant with the output pins, so PA doesn't know > > how to interpret it, hence it's ignored. > > Yes, but do we have any error checks in the hw_params or trigger cases > with the legacy driver? No, it just continues playing without the actual output. Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
