Hans Verkuil, Fri, Mar 13, 2020 11:52:03 +0100: > On 3/13/20 11:26 AM, Alex Riesen wrote: > > Hans Verkuil, Fri, Mar 13, 2020 09:16:11 +0100: > >> Generally an hdmi driver will configure the i2s audio automatically, which is > >> typically connected to the SoC and controlled by the ALSA driver of the SoC, > >> but there may well be missing features (audio never got a lot of attention in > >> hdmi receivers). So what I would like to know is: what features are missing? > > > > Well, the audio is missing. The current adv748x driver does not export the > > audio features of the device at all. There is no code to enable the I2S audio > > output and it is disabled (all clock and the data lines) by default. > > Sorry, I was vague in my question. Obviously that needs to be added, but besides > adding the low-level i2s support I was wondering if there are additional things > that need to be exposed to userspace in order for audio to fully work. None that I can't expose over the DAI interfaces: clocks, I2S format, mute/demute ... All covered. > >> Anything missing can likely be resolved by adding HDMI audio specific V4L2 controls, > >> which would be the right approach for this. > >> > >> So I would expect to see a proposal for V4L2_CID_DV_RX_AUDIO_ controls to be > >> added here: > >> > >> https://linuxtv.org/downloads/v4l-dvb-apis-new/uapi/v4l/ext-ctrls-dv.html > > > > This seems to be an explicitly "digital video" control class. And it has no > > control option for mute. Or did you mean a similarly structured new class for > > "digital audio"? > > There are no DV_ audio controls at all today. So any new audio controls would be > added to the DV class. But if there is nothing that needs to be exposed, then > nothing needs to be added :-) Ah, alright. I shall keep an eye on it, maybe I shall find something to expose :) Regards, Alex
