drm/dp: Introduce EDID-based quirks

The whole point of using OUIs is so that we can recognize certain
devices and potentially apply quirks for them. Normally this should work
quite well, but there appears to be quite a number of laptop panels out
there that will fill the OUI but not the device ID. As such, for devices
like this I can't imagine it's a very good idea to try relying on OUIs
for applying quirks. As well, some laptop vendors have confirmed to us
that their panels have this exact issue.

So, let's introduce the ability to apply DP quirks based on EDID
identification. We reuse the same quirk bits for OUI-based quirks, so
that callers can simply check all possible quirks using
drm_dp_has_quirk().

Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Adam Jackson <ajax@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200211183358.157448-2-lyude@redhat.com

1 files changed, 8 insertions, 3 deletions

diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 262faf9e5e94..7f5dd2ee4a94 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -1495,13 +1495,16 @@ struct drm_dp_desc {
 
 int drm_dp_read_desc(struct drm_dp_aux *aux, struct drm_dp_desc *desc,
 		     bool is_branch);
+u32 drm_dp_get_edid_quirks(const struct edid *edid);
 
 /**
  * enum drm_dp_quirk - Display Port sink/branch device specific quirks
  *
  * Display Port sink and branch devices in the wild have a variety of bugs, try
  * to collect them here. The quirks are shared, but it's up to the drivers to
- * implement workarounds for them.
+ * implement workarounds for them. Note that because some devices have
+ * unreliable OUIDs, the EDID of sinks should also be checked for quirks using
+ * drm_dp_get_edid_quirks().
  */
 enum drm_dp_quirk {
 	/**
@@ -1537,14 +1540,16 @@ enum drm_dp_quirk {
 /**
  * drm_dp_has_quirk() - does the DP device have a specific quirk
  * @desc: Device decriptor filled by drm_dp_read_desc()
+ * @edid_quirks: Optional quirk bitmask filled by drm_dp_get_edid_quirks()
  * @quirk: Quirk to query for
  *
  * Return true if DP device identified by @desc has @quirk.
  */
 static inline bool
-drm_dp_has_quirk(const struct drm_dp_desc *desc, enum drm_dp_quirk quirk)
+drm_dp_has_quirk(const struct drm_dp_desc *desc, u32 edid_quirks,
+		 enum drm_dp_quirk quirk)
 {
-	return desc->quirks & BIT(quirk);
+	return (desc->quirks | edid_quirks) & BIT(quirk);
 }
 
 #ifdef CONFIG_DRM_DP_CEC