[pulseaudio-discuss] [PATCH 0/3] Read HDMI ELD info and set a port property

[David Henningsson]

On 02/17/2013 02:29 AM, Fengguang Wu wrote:
> Hi David,
>
> On Fri, Feb 15, 2013 at 11:02:31PM -0600, Pierre-Louis Bossart wrote:
>>
>>> There's a bummer though. On the one machine I've tested this, the ELD is not
>>> immediately available, so hotplugging doesn't work. It also looks like there's no
>>> event being sent out from the kernel when ELD has become available, so we probably
>
> You may print a debug messages in the graphics driver's interrupt handler
> for every hotplug event to check if the hotplug event is not raised
> from hardware at all, or (likely) get lost somewhere later when
> passing it to the audio driver.
>
>>> need to add some kind of timer - but I'm not sure exactly what time ranges should
>>> work for all machines. Pierre, do you know?
>>
>> Trying rebooting with the HDMI cable plugged and see if this works.
>> I know my IbexPeak hardware only detects HDMI at boot, probably some
>> BIOS issue. Fengguang might be able to help?
>
> Good tip. It's worth trying, as I noticed the same phenomenon in my
> past HDMI tests (HDMI not useable at all if hot-plugged after boot).
> For the boot issue, it may be because of some unknown BIOS hack, or
> something the graphics driver failed to initialize (or did it right).

To clarify: When hotplugging, the ELD does show up, it just doesn't do 
that at the same time as the jack does, that is, eld might become valid 
at a later time compared to the "precense" bit.

I looked at the kernel code now, and it seems like there is a repoll 
mechanism to fetch the ELD information. It shouldn't be too difficult to 
insert a snd_ctl_notify when the ELD control changes (as Tanu suggests), 
I will look into this next week hopefully.


-- 
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic