[PATCH] drm/bridge: dw-hdmi: fix EDID parsing

[Luís Mendes]

I've verified that dw_hdmi tracks when there is a monitor connected or
not and reacts to it, there are logs that are generated when the
TV/Monitor goes into standby and this is true even if DDC cannot be
read.
My original problem is that if the EDID data cannot be read then
dw_hdmi will enter DVI mode confiuration, with which I cannot get
sound, other than that the driver works properly.

On Thu, Nov 9, 2017 at 4:28 PM, Russell King - ARM Linux
<linux at armlinux.org.uk> wrote:
> On Thu, Nov 09, 2017 at 05:01:35PM +0200, Jani Nikula wrote:
>> On Thu, 09 Nov 2017, Luís Mendes <luis.p.mendes at gmail.com> wrote:
>> > Hi Jani,
>> >
>> > I tried:
>> > git clone git://people.freedesktop.org/~airlied/linux -b drm-next
>> > --depth=1 --single-branch
>> >
>> > I got this:
>> > EDID isn't loaded from file
>> >
>> > # cat /proc/cmdline
>> > console=ttymxc0,115200 root=/dev/sda2 rw video=HDMI-A-1:1920x1080M at 60
>> > drm.edid_firmware=edid/ktc_edid.bin dw_hdmi.dyndbg=+pfl cma=128M
>>
>> Please try adding D at the end of your video= parameter to force
>> connector on. Otherwise it'll do a ddc probe which apparently fails with
>> your display.
>
> I do hope you're not converting dw-hdmi to use DDC probing and having it
> ignore the hotplug signal.  dw-hdmi has to work with AV setups, which
> include an AV receiver, and that includes the AV receiver modifying the
> HDMI data when:
>
> (a) the TV is turned off or on.
> (b) the AV receiver is placed into or out of standby
>
> and it informs sources by pulsing the HDMI HPD signal, as per the HDMI
> specification.  Proving the presence of DDC as a means of detection
> won't pick up on these changes, and will cause a regression in the
> driver.
>
> --
> RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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