Question regarding HDMI Audio support on i.MX6 with vanilla kernel

[Luís Mendes]

Hi,

Replies in between...

Regards,
Luís

On Tue, Nov 7, 2017 at 5:03 PM, Russell King - ARM Linux <
linux at armlinux.org.uk> wrote:

> Hi Luís,
>
> On Tue, Nov 07, 2017 at 04:53:02PM +0000, Luís Mendes wrote:
> > Hi Russell,
> >
> > I've just tested my Wandboard Rev.D1 with a Samsung monitor PX2370,
> model:
> > LS23WHEKFV/EN which has HDMI with audio (has an audio pass-through with
> an
> > optical IEC958 connector and an analog stereo audio jack which can be
> > connected to an amplifier, despite the monitor has no speakers embedded
> to
> > it) that provides no EDID information, thus I had to force the EDID data
> > from my home TV for the audio to work.
>
> What do you mean "provides no EDID information" - you mean there's no
> EDID at all from the monitor, or it's just missing the HDMI vendor
> block?  I'd find it hard to accept that there's no EDID information at
> all from the monitor.
>
> Can you provide me with whatever EDID information the monitor does give
> please, preferably in binary format.  Thanks.
>

I got no EDID at all from the monitor.
get-edid returns:
No EDID on bus 0
No EDID on bus 1
No EDID on bus 2

hexdump -C /sys/class/drm/card1-HDMI-A-1/edid
is empty


>
> > This made me think the kernel option has_audio={-1,0,1} would be
> > appropriate for these cases. I know that you don't find this idea so
> good,
> > but for these cases would be nice. If you want I can provide a patch for
> > this.
> > What do you say?
>
> I disagree - if the monitor supports audio, but doesn't advertise in
> the EDID that it supports audio, it isn't a source device problem,
> and it isn't a source driver problem either.  It's a generic problem.
>
> Consider if you connect this monitor to some other device, such as a
> PC running Intel graphics - should the i915 driver also spring up a
> "has_audio" option as well?
>
> Would it not be more sensible for this to be handled generically
> within DRM?
>

You're right it makes more sense. I wasn't thinking in generic terms...

>
> Regards,
>
> --
> RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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> up
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>
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