drm/i915/dp: Track source OUI validity explicitly

While updating the source OUI on the sink the driver should avoid
writing the OUI if it's already up-to-date to prevent the sink from
resetting itself in response to the update. On eDP - the only output
type where the OUI was updated so far - the driver ensured this by
comparing the current source OUI DPCD register values with the expected
Intel OUI value, skipping the update in case of a match. On some non-eDP
sinks - at least on Synaptics branch devices - this method doesn't work,
since the source OUI DPCD registers read back as all 0, even after
updating the registers.

Handle the above kind of sinks by tracking when the OUI was updated and
so should be valid, regardless of what the DPCD registers contain.

eDP sinks reset the written source OUI value when the panel power is
disabled, invalidate the OUI state accordingly.

This is required by a follow-up patch updating the source OUI for
non-eDP sink types as well.

v2: Fix setting intel_dp::oui_valid=true, if the DPCD register contains
    already the expected value.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241025160259.3088727-5-imre.deak@intel.com

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
index 4efb9605a50e..48f10876be65 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.h
+++ b/drivers/gpu/drm/i915/display/intel_dp.h
@@ -189,6 +189,7 @@ void intel_dp_check_frl_training(struct intel_dp *intel_dp);
 void intel_dp_pcon_dsc_configure(struct intel_dp *intel_dp,
 				 const struct intel_crtc_state *crtc_state);
 
+void intel_dp_invalidate_source_oui(struct intel_dp *intel_dp);
 void intel_dp_wait_source_oui(struct intel_dp *intel_dp);
 int intel_dp_output_bpp(enum intel_output_format output_format, int bpp);