[adv7511] Adding audio to transmitter driver

[Laurent Pinchart]

Hi Jose,

(CC'ing Morimoto-san)

On Monday 15 February 2016 19:13:11 Jose Abreu wrote:
> Hi all,
> 
> I am an employee at Synopsys and as part of our IP Prototyping Kits we are
> adding audio support to the ADV7511 HDMI transmitter. Our work is based on
> the Analog Devices kernel tree available at:
> https://github.com/analogdevicesinc/linux/blob/xcomm_zynq/drivers/gpu/drm/i
> 2c/adv7511_audio.c.
> 
> Currently we are facing an difficulty regarding the organization of the
> driver. Analog Devices compiles both audio and video in a single global
> driver but we were wondering if its better to separate audio from video and
> make them as separate Kconfig entries.
> 
> As we expect to introduce this in the mainline we are asking you for
> suggestions or comments about this matter. Is it any driver in the mainline
> that faces the same situation so we can base our work? What do you think
> its the best solution? Enable audio and video at the same time or make them
> separate entries?

As the ADV7511 is an I2C chip and will bind to a single driver, splitting 
audio and video in two really independent drivers would be quite cumbersome. 
It could be done by creating a third driver that instantiates two platform 
devices, one for audio and the other one for video, exporting an API for thos 
two drivers to arbitrate access to shared resources (mostly registers). That 
could be done, but seems a bit overkill to me.

I would keep audio and video in a single driver, but make audio support 
optional through a Kconfig option. Video support could also be made optional 
in a similar fashion, is it possible to transfer audio over HDMI without a 
video stream ?

An interesting issue that also needs to be addressed is how to design DT 
bindings for the ADV7511 node.

-- 
Regards,

Laurent Pinchart