From 5efd407674068dede403551bea3b0b134c32513a Mon Sep 17 00:00:00 2001
From: Jani Nikula <jani.nikula@intel.com>
Date: Wed, 13 Jan 2016 16:35:20 +0200
Subject: [PATCH] drm/i915/dp: fall back to 18 bpp when sink capability is
unknown
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Per DP spec, the source device should fall back to 18 bpp, VESA range
RGB when the sink capability is unknown. Fix the color depth
clamping. 18 bpp color depth should ensure full color range in automatic
mode.
The clamping has been HDMI specific since its introduction in
commit 996a2239f93b03c5972923f04b097f65565c5bed
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Fri Apr 19 11:24:34 2013 +0200
drm/i915: Disable high-bpc on pre-1.4 EDID screens
Cc: stable@vger.kernel.org
Reported-and-tested-by: Dihan Wickremasuriya <nayomal@gmail.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=105331
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1452695720-7076-1-git-send-email-jani.nikula@intel.com
(cherry picked from commit 013dd9e038723bbd2aa67be51847384b75be8253)
---
drivers/gpu/drm/i915/intel_display.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 2f00828ccc6e9..002ce89de412d 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -12075,11 +12075,21 @@ connected_sink_compute_bpp(struct intel_connector *connector,
pipe_config->pipe_bpp = connector->base.display_info.bpc*3;
}
- /* Clamp bpp to 8 on screens without EDID 1.4 */
- if (connector->base.display_info.bpc == 0 && bpp > 24) {
- DRM_DEBUG_KMS("clamping display bpp (was %d) to default limit of 24\n",
- bpp);
- pipe_config->pipe_bpp = 24;
+ /* Clamp bpp to default limit on screens without EDID 1.4 */
+ if (connector->base.display_info.bpc == 0) {
+ int type = connector->base.connector_type;
+ int clamp_bpp = 24;
+
+ /* Fall back to 18 bpp when DP sink capability is unknown. */
+ if (type == DRM_MODE_CONNECTOR_DisplayPort ||
+ type == DRM_MODE_CONNECTOR_eDP)
+ clamp_bpp = 18;
+
+ if (bpp > clamp_bpp) {
+ DRM_DEBUG_KMS("clamping display bpp (was %d) to default limit of %d\n",
+ bpp, clamp_bpp);
+ pipe_config->pipe_bpp = clamp_bpp;
+ }
}
}
--
2.39.5