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

[Luís Mendes]

On Tue, Nov 7, 2017 at 6:49 PM, Russell King - ARM Linux <
linux at armlinux.org.uk> wrote:

> On Tue, Nov 07, 2017 at 05:58:19PM +0000, Luís Mendes wrote:
> > On Tue, Nov 7, 2017 at 5:45 PM, Russell King - ARM Linux <
> > linux at armlinux.org.uk> wrote:
> > > Can you confirm that it also gives no EDID when plugged into another
> > > machine?  I don't see evidence via google that other people have a
> > > problem with the monitor - and in this day and age, a monitor missing
> > > all EDID is just completely perverse, especially if it has a HDMI
> > > socket.  (EDID is basically a requirement for HDMI, it isn't optional.)
> >
> > You are right... the monitor does have EDID. I've just connected it to my
> > laptop. Binary in attachment, parsed edid below.
>
> Thanks.
>
> Your EDID block contains this CEA extension:
>
> 00000080  02 03 1c f3 48 90 04 1f  05 14 13 03 12 23 09 07
> |....H........#..|
> 00000090  07 83 01 00 00 66 03 0c  00 10 00 80 01 1d 80 d0
> |.....f..........|
> 000000a0  72 1c 16 20 10 2c 25 80  a0 5a 00 00 00 9e 01 1d  |r..
> .,%..Z......|
> 000000b0  80 18 71 1c 16 20 58 2c  25 00 a0 5a 00 00 00 9e  |..q..
> X,%..Z....|
> 000000c0  01 1d 00 bc 52 d0 1e 20  b8 28 55 40 a0 5a 00 00  |....R.. .(U@
> .Z..|
> 000000d0  00 1e 01 1d 00 72 51 d0  1e 20 6e 28 55 00 a0 5a  |.....rQ..
> n(U..Z|
> 000000e0  00 00 00 1e 8c 0a d0 90  20 40 31 20 0c 40 55 00  |........ @1
> . at U.|
> 000000f0  a0 5a 00 00 00 18 00 00  00 00 00 00 00 00 00 75
> |.Z.............u|
>
> which gives:
>
> 48 90 04 1f 05 14 13 03 12 <= video block
> 23 09 07 07 <= audio block (32kHz, 44.1kHz, 48kHz)
> 83 01 00 00 <= speaker allocation block
> 66 03 0c 00 10 00 80 <= HDMI vendor block
>
> That looks all good from the HDMI audio point of view.
>
> > > I wonder if your board is missing something - maybe the 5V supply to
> > > the HDMI socket is missing (which is a requirement in the HDMI spec
> > > for the DDC bus to be usable.)
> >
> > Yes, it looks like there is something with the board. Although my home
> TVs
> > now work since I changed to i2c2.
>
> Which board is this?  Are any schematics available?
>

You don't need to waste your time with this issue... I will develop my own
hardware later, my own carrier board, it is not a big issue for me.
I was just speaking about this in terms of having a workaround in the
device driver for situations like this, but since you say that all HDMI
monitors must have EDID then this doesn't make much sense to change,
forcing the EDID is enough.

Thanks.



>
> --
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>
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