drm/edid: Reset more of the display info

BugLink: http://bugs.launchpad.net/bugs/1778265
commit 1f6b8eef11c3d097bc8a6b2bbb868eb47ec6f7d8 upstream.

We're currently failing to reset everything in display_info.hdmi
which will potentially cause us to use stale information when
swapping monitors. Eg. if the user replaces a HDMI 2.0 monitor
with a HDMI 1.x monitor we will continue to think that the monitor
supports scrambling. That will lead to a black screen since the
HDMI 1.x monitor won't understand the scrambled signal.

Fix the problem by clearing display_info.hdmi fully. And while at
eliminate some duplicated code by calling drm_reset_display_info()
in drm_add_display_info().

Cc: stable@vger.kernel.org
Cc: Antony Chen <antonychen@qnap.com>
Cc: Shashank Sharma <shashank.sharma@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105655
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180424130250.7028-1-ville.syrjala@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: Antony Chen <antonychen@qnap.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 96afdb4d3ecf2c855d382f7501fcd6e50b11e4f6..d83e27557b3a27bf02de95a3e8310e4263312d7e 100644 (file)
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -4421,6 +4421,7 @@ drm_reset_display_info(struct drm_connector *connector)
        info->cea_rev = 0;
        info->max_tmds_clock = 0;
        info->dvi_dual = false;
+       memset(&info->hdmi, 0, sizeof(info->hdmi));
 
        info->non_desktop = 0;
 }
@@ -4432,16 +4433,11 @@ u32 drm_add_display_info(struct drm_connector *connector, const struct edid *edi
 
        u32 quirks = edid_get_quirks(edid);
 
+       drm_reset_display_info(connector);
+
        info->width_mm = edid->width_cm * 10;
        info->height_mm = edid->height_cm * 10;
 
-       /* driver figures it out in this case */
-       info->bpc = 0;
-       info->color_formats = 0;
-       info->cea_rev = 0;
-       info->max_tmds_clock = 0;
-       info->dvi_dual = false;
-
        info->non_desktop = !!(quirks & EDID_QUIRK_NON_DESKTOP);
 
        DRM_DEBUG_KMS("non_desktop set to %d\n", info->non_desktop);