[PATCH 1/2] drm/edid: Add a EDID edp panel quirk for forcing max lane count

[Manasi Navare]

For certain eDP 1.4 panels, we need to use max lane count for the
link training to succeed.

This patch adds a EDID quirk for such eDP panels using
their vendor ID and product ID to force using max lane count in the driver.

Cc: Clint Taylor <Clinton.A.Taylor at intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Tested-by: Albert Astals Cid <aacid at kde.org>
Tested-by: Emanuele Panigati <ilpanich at gmail.com>
Tested-by: Ralgor <ralgorfdb at compuspex.org>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109959
Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
---
 drivers/gpu/drm/drm_edid.c  | 10 ++++++++++
 include/drm/drm_connector.h |  5 +++++
 2 files changed, 15 insertions(+)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 2c22ea446075..fbc661806484 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -82,6 +82,8 @@
 #define EDID_QUIRK_FORCE_10BPC			(1 << 11)
 /* Non desktop display (i.e. HMD) */
 #define EDID_QUIRK_NON_DESKTOP			(1 << 12)
+/* Force max lane count */
+#define EDID_QUIRK_FORCE_MAX_LANE_COUNT		(1 << 13)
 
 struct detailed_mode_closure {
 	struct drm_connector *connector;
@@ -189,6 +191,10 @@ static const struct edid_quirk {
 
 	/* OSVR HDK and HDK2 VR Headsets */
 	{ "SVR", 0x1019, EDID_QUIRK_NON_DESKTOP },
+
+	/* SHP eDP 1.4 panel only works with max lane count */
+	{ "SHP", 0x149a, EDID_QUIRK_FORCE_MAX_LANE_COUNT },
+	{ "SHP", 0x148e, EDID_QUIRK_FORCE_MAX_LANE_COUNT },
 };
 
 /*
@@ -4463,6 +4469,7 @@ drm_reset_display_info(struct drm_connector *connector)
 	memset(&info->hdmi, 0, sizeof(info->hdmi));
 
 	info->non_desktop = 0;
+	info->force_max_lane_count = 0;
 }
 
 u32 drm_add_display_info(struct drm_connector *connector, const struct edid *edid)
@@ -4744,6 +4751,9 @@ int drm_add_edid_modes(struct drm_connector *connector, struct edid *edid)
 	if (quirks & EDID_QUIRK_FORCE_12BPC)
 		connector->display_info.bpc = 12;
 
+	if (quirks & EDID_QUIRK_FORCE_MAX_LANE_COUNT)
+		connector->display_info.force_max_lane_count = true;
+
 	return num_modes;
 }
 EXPORT_SYMBOL(drm_add_edid_modes);
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index 02a131202add..45436d40ffe3 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -457,6 +457,11 @@ struct drm_display_info {
 	 * @non_desktop: Non desktop display (HMD).
 	 */
 	bool non_desktop;
+
+	/**
+	 * @force_max_lane_count: Link training requires max lane count to pass
+	 */
+	bool force_max_lane_count;
 };
 
 int drm_display_info_set_bus_formats(struct drm_display_info *info,
-- 
2.19.1