Re: [Intel-gfx] [PATCH v3 00/22] drm/i915: Init DDI ports in VBT order

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Feb 22, 2023 at 01:02:05AM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> I just wanted to init DDI ports in VBT child device order
> without any up front assumptions about which conflicting
> child device defition is valid. That is pretty much what
> we need to do for the ADL laptops with the phantom eDP vs.
> native HDMI on DDI B.
> 
> However that approach doesn't work for some of the weird
> SKL boards that have a phantom eDP on DDI A+AUX A and
> and a real DP->VGA converter on DDI E+AUX A. For those
> I had to introduce HPD live status check during eDP init.
> 
> One of the remaining concerns I still have is what happens
> when we encounter VBTs with more AUX CH/DDC pin conflicts?
> I think what we might want to do eventually is ignore the
> conflicts as much as possible, and just init everything
> based on VBT, trusting HPD to take care of things in the
> end. That of course does have certain issues wrt. connector
> forcing, but dunno if we can avoid those at all.
> 
> Also I think we need to nuke all the platform default AUX
> CH/DDC pin stuff, or at least only try to utilize those
> only once we've consumed the VBT fully.
> 
> v2: Fix SKL DDI A HPD live state
> v3: Replace AUX CH/DDC pin sanitation with availability checks

OK, it looks like this is finally doing something
sane on pretty much all machines.

The only slight concern left is on bat-rplp-1:
 [drm:intel_dp_aux_ch [i915]] [ENCODER:257:DDI TC2/PHY TC2] Using AUX CH E (platform default)
 [drm:intel_power_well_enable [i915]] enabling AUX_USBC2
 [drm:intel_power_well_disable [i915]] disabling AUX_USBC2
 [drm:intel_power_well_enable [i915]] enabling AUX_USBC2
 [drm:intel_tc_port_init_mode [i915]] Port E/TC#2: init mode (legacy)
 [drm:intel_hdmi_init_connector [i915]] Adding HDMI connector on [ENCODER:257:DDI TC2/PHY TC2]
 [drm:intel_hdmi_init_connector [i915]] [ENCODER:257:DDI TC2/PHY TC2] Using DDC pin 0xa (VBT)

So we're still having to use the platform default AUX CH
for this HDMI TC legacy port. But I guess that should be
relatively risk free as cross-wiring the TC ports in any
way doesn't seem like something that should happen. Might
not even be possible since a lot of the stuff for these
is internal to the chip.

-- 
Ville Syrjälä
Intel