On Thu, 13 Nov 2014 17:44:38 +0200 Tomi Valkeinen <tomi.valkeinen@xxxxxx> wrote: [snip] > >> a) Always keep the audio device operational, no matter what is the > >> status of the video side. How should this work if the HDMI videomode or > >> the HDMI monitor does not support audio? Is it desirable that the > >> userspace has no idea that the audio is not actually going anywhere? > >> > >> b) Remove the audio device when audio support is not available. This > >> kind of makes sense, as, well, there's no possibility for audio output. > >> But maybe this is not how linux sound devices are supposed to behave? > >> > >> c) Return errors when playback is attempted when audio support is not > >> available. Again, this kind of makes sense, as audio playback is not > >> possible. But maybe this is also not how audio devices generally work. > >> > >> Jyri, were there some other options we discussed? > >> > >> Currently, the OMAP HDMI version does c). It's the easiest solution for us. > > > > Same for me, but checking the audio capability is done on audio streaming > > start only. > > Hmm, I understood you have option a)? You said "I even let audio > streaming start when the HDMI cable is > disconnected". The option a) is the one of the patch, but I am moving towards option c). > With "audio support is not available" I mean also the case when the > cable is not connected, as then we don't have EDID information, and thus > we don't have a HDMI monitor with audio support on the other end. What I was saying is: when the cable is connected, all audio/video parameters are known. Then, when the cable is disconnected, there is no reason, a priori, to change these parameters, and audio/video streaming may continue. The problem might be raised later when an other monitor with different parameters will be connected. > So to clarify, our driver only has "audio support available" if: > - we successfully read EDID > - EDID shows it's a HDMI monitor > - EDID shows it has audio support for the format we support (this we > don't actually do yet) > > Otherwise we default to DVI, which means no audio. > > If, at any point, the situation changes to "no audio support available", > the audio playback is aborted and starting new audio playback fails. [snip] So, to summarize, you need the information 'audio support available' on the audio side. It should not be difficult to export a function in the generic HDMI driver for this job. This function would have the following arguments: - device (child device of the HDMI transmitter) - pin (output widget name) - status (enable/disable) and would: - set the pin status so that the HDMI output would be included or not in the audio path, and - abort audio streaming on disabling audio. -- Ken ar c'hentañ | ** Breizh ha Linux atav! ** Jef | http://moinejf.free.fr/ -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
