drm/gma500/psb: Actually use VBT mode when it is found

With LVDS we were incorrectly picking the pre-programmed mode instead of
the prefered mode provided by VBT. Make sure we pick the VBT mode if
one is provided. It is likely that the mode read-out code is still wrong
but this patch fixes the immediate problem on most machines.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78562
Cc: <stable@vger.kernel.org>
Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170418114332.12183-1-patrik.r.jakobsson@gmail.com

diff --git a/drivers/gpu/drm/gma500/psb_intel_lvds.c b/drivers/gpu/drm/gma500/psb_intel_lvds.c
index 0066fe7..be3eefe 100644 (file)
--- a/drivers/gpu/drm/gma500/psb_intel_lvds.c
+++ b/drivers/gpu/drm/gma500/psb_intel_lvds.c
@@ -759,20 +759,23 @@ void psb_intel_lvds_init(struct drm_device *dev,
                if (scan->type & DRM_MODE_TYPE_PREFERRED) {
                        mode_dev->panel_fixed_mode =
                            drm_mode_duplicate(dev, scan);
+                       DRM_DEBUG_KMS("Using mode from DDC\n");
                        goto out;       /* FIXME: check for quirks */
                }
        }
 
        /* Failed to get EDID, what about VBT? do we need this? */
-       if (mode_dev->vbt_mode)
+       if (dev_priv->lfp_lvds_vbt_mode) {
                mode_dev->panel_fixed_mode =
-                   drm_mode_duplicate(dev, mode_dev->vbt_mode);
+                       drm_mode_duplicate(dev, dev_priv->lfp_lvds_vbt_mode);
 
-       if (!mode_dev->panel_fixed_mode)
-               if (dev_priv->lfp_lvds_vbt_mode)
-                       mode_dev->panel_fixed_mode =
-                               drm_mode_duplicate(dev,
-                                       dev_priv->lfp_lvds_vbt_mode);
+               if (mode_dev->panel_fixed_mode) {
+                       mode_dev->panel_fixed_mode->type |=
+                               DRM_MODE_TYPE_PREFERRED;
+                       DRM_DEBUG_KMS("Using mode from VBT\n");
+                       goto out;
+               }
+       }
 
        /*
         * If we didn't get EDID, try checking if the panel is already turned
@@ -789,6 +792,7 @@ void psb_intel_lvds_init(struct drm_device *dev,
                if (mode_dev->panel_fixed_mode) {
                        mode_dev->panel_fixed_mode->type |=
                            DRM_MODE_TYPE_PREFERRED;
+                       DRM_DEBUG_KMS("Using pre-programmed mode\n");
                        goto out;       /* FIXME: check for quirks */
                }
        }