Re: [Intel-gfx] [PATCH 01/15] drm/i915/hdmi: do dual mode detect only if connected

[Jani Nikula <jani.nikula@intel.com>]

On Wed, 19 Oct 2022, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> On Thu, Oct 13, 2022 at 10:24:54PM +0300, Ville Syrjälä wrote:
>> On Thu, Oct 13, 2022 at 09:41:21PM +0300, Ville Syrjälä wrote:
>> > On Tue, Oct 11, 2022 at 04:49:35PM +0300, Jani Nikula wrote:
>> > > -	intel_hdmi_dp_dual_mode_detect(connector, edid != NULL);
>> > > -
>> > > -	intel_display_power_put(dev_priv, POWER_DOMAIN_GMBUS, wakeref);
>> > > -
>> > >  	to_intel_connector(connector)->detect_edid = edid;
>> > >  	if (edid && edid->input & DRM_EDID_INPUT_DIGITAL) {
>> > 
>> > We didn't have this digital input thing before. What happens with
>> > HDMI->VGA dongles for example?
>> > 
>> > Hmm. This whole thing might already be broken on those. I suspect
>> > I've only used my HDMI->VGA dongle on LSPCON machines, so never
>> > noticed this. Need to go plug that thing into a native HDMI port...
>> 
>> Except I must have left it elsewhere since I can't find it here.
>> So can't test right now unfortunately.
>> 
>> I first thought this digital check thing might be due to
>> the DVI-I shenanigans in intel_crt_detect_ddc(), but that
>> was added for am unspecified gen2 machine in commit f5afcd3dd0dc
>> ("drm/i915/crt: Check for a analog monitor in case of DVI-I")
>> so not even relevant here. And I don't think I've ever seen
>> a g4x+ machine with an actual DVI-I port.
>
> Good news everyone, I found such a board: Intel DG43GT.
> Well, I didn't physically find one but I found the manual
> online. And some coreboot repo even had the vbt handily
> available. And yes, it does show the same DDC pins being
> used for the DVI-D port and CRT port. So I guess given
> that these digital checks do make some sense.

So what's the conclusion wrt the patch at hand?

BR,
Jani.

-- 
Jani Nikula, Intel Open Source Graphics Center