From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Unfortunately even the HPD based detection added in
commit cfe5bdfb27fa ("drm/i915: Check HPD live state during eDP probe")
fails to detect that the VBT's eDP/DDI-A is a ghost on
Asus B360M-A (CFL+CNP). On that board eDP/DDI-A has its HPD
asserted despite nothing being actually connected there :(
The straps/fuses also indicate that the eDP port is present.
So if one boots with a VGA monitor connected the eDP probe will
mistake the DP->VGA converter hooked to DDI-E for an eDP panel
on DDI-A.
As a last resort check what kind of DP device we've detected,
and if it looks like a DP->VGA converter then conclude that
the eDP port should be ignored.
Cc: stable@xxxxxxxxxxxxxxx
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9636
Fixes: cfe5bdfb27fa ("drm/i915: Check HPD live state during eDP probe")
Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_dp.c | 28 +++++++++++++++++++------
1 file changed, 22 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 54bd0bffa9f0..14ee05fabd05 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -6277,8 +6277,7 @@ static bool intel_edp_init_connector(struct intel_dp *intel_dp,
* (eg. Acer Chromebook C710), so we'll check it only if multiple
* ports are attempting to use the same AUX CH, according to VBT.
*/
- if (intel_bios_dp_has_shared_aux_ch(encoder->devdata) &&
- !intel_digital_port_connected(encoder)) {
+ if (intel_bios_dp_has_shared_aux_ch(encoder->devdata)) {
/*
* If this fails, presume the DPCD answer came
* from some other port using the same AUX CH.
@@ -6286,10 +6285,27 @@ static bool intel_edp_init_connector(struct intel_dp *intel_dp,
* FIXME maybe cleaner to check this before the
* DPCD read? Would need sort out the VDD handling...
*/
- drm_info(&dev_priv->drm,
- "[ENCODER:%d:%s] HPD is down, disabling eDP\n",
- encoder->base.base.id, encoder->base.name);
- goto out_vdd_off;
+ if (!intel_digital_port_connected(encoder)) {
+ drm_info(&dev_priv->drm,
+ "[ENCODER:%d:%s] HPD is down, disabling eDP\n",
+ encoder->base.base.id, encoder->base.name);
+ goto out_vdd_off;
+ }
+
+ /*
+ * Unfortunately even the HPD based detection fails on
+ * eg. Asus B360M-A (CFL+CNP), so as a last resort fall
+ * back to checking for a VGA branch device. Only do this
+ * on known affected platforms to minimize false positives.
+ */
+ if (DISPLAY_VER(dev_priv) == 9 && drm_dp_is_branch(intel_dp->dpcd) &&
+ (intel_dp->dpcd[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_TYPE_MASK) ==
+ DP_DWN_STRM_PORT_TYPE_ANALOG) {
+ drm_info(&dev_priv->drm,
+ "[ENCODER:%d:%s] VGA converter detected, disabling eDP\n",
+ encoder->base.base.id, encoder->base.name);
+ goto out_vdd_off;
+ }
}
mutex_lock(&dev_priv->drm.mode_config.mutex);
--
2.41.0
