[PATCH 07/10] drm: edid: Don't add inferred modes with higher resolution

[Dave Chiluk]

From: Takashi Iwai <tiwai at suse.de>

BugLink: http://bugs.launchpad.net/bugs/1109112

When a monitor EDID doesn't give the preferred bit, driver assumes
that the mode with the higest resolution and rate is the preferred
mode.  Meanwhile the recent changes for allowing more modes in the
GFT/CVT ranges give actually more modes, and some modes may be over
the native size.  Thus such a mode would be picked up as the preferred
mode although it's no native resolution.

For avoiding such a problem, this patch limits the addition of
inferred modes by checking not to be greater than other modes.
Also, it checks the duplicated mode entry at the same time.

Reviewed-by: Adam Jackson <ajax at redhat.com>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
Signed-off-by: Dave Airlie <airlied at redhat.com>
(cherry picked from commit 7b668ebe2fce517873b0c28dd70c10fef1d3dc2f)

Signed-off-by: David Chiluk <chiluk at canonical.com>
---
 drivers/gpu/drm/drm_edid.c |   27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 8b72d9e..a0666f0 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1027,6 +1027,24 @@ mode_in_range(const struct drm_display_mode *mode, struct edid *edid,
 	return true;
 }
 
+static bool valid_inferred_mode(const struct drm_connector *connector,
+				const struct drm_display_mode *mode)
+{
+	struct drm_display_mode *m;
+	bool ok = false;
+
+	list_for_each_entry(m, &connector->probed_modes, head) {
+		if (mode->hdisplay == m->hdisplay &&
+		    mode->vdisplay == m->vdisplay &&
+		    drm_mode_vrefresh(mode) == drm_mode_vrefresh(m))
+			return false; /* duplicated */
+		if (mode->hdisplay <= m->hdisplay &&
+		    mode->vdisplay <= m->vdisplay)
+			ok = true;
+	}
+	return ok;
+}
+
 /*
  * XXX If drm_dmt_modes ever regrows the CVT-R modes (and it will) this will
  * need to account for them.
@@ -1040,7 +1058,8 @@ drm_dmt_modes_for_range(struct drm_connector *connector, struct edid *edid,
 	struct drm_device *dev = connector->dev;
 
 	for (i = 0; i < drm_num_dmt_modes; i++) {
-		if (mode_in_range(drm_dmt_modes + i, edid, timing)) {
+		if (mode_in_range(drm_dmt_modes + i, edid, timing) &&
+		    valid_inferred_mode(connector, drm_dmt_modes + i)) {
 			newmode = drm_mode_duplicate(dev, &drm_dmt_modes[i]);
 			if (newmode) {
 				drm_mode_probed_add(connector, newmode);
@@ -1078,7 +1097,8 @@ drm_gtf_modes_for_range(struct drm_connector *connector, struct edid *edid,
 		newmode = drm_gtf_mode(dev, m->w, m->h, m->r, 0, 0);
 
 		fixup_mode_1366x768(newmode);
-		if (!mode_in_range(newmode, edid, timing)) {
+		if (!mode_in_range(newmode, edid, timing) ||
+		    !valid_inferred_mode(connector, newmode)) {
 			drm_mode_destroy(dev, newmode);
 			continue;
 		}
@@ -1104,7 +1124,8 @@ drm_cvt_modes_for_range(struct drm_connector *connector, struct edid *edid,
 		newmode = drm_cvt_mode(dev, m->w, m->h, m->r, rb, 0, 0);
 
 		fixup_mode_1366x768(newmode);
-		if (!mode_in_range(newmode, edid, timing)) {
+		if (!mode_in_range(newmode, edid, timing) ||
+		    !valid_inferred_mode(connector, newmode)) {
 			drm_mode_destroy(dev, newmode);
 			continue;
 		}
-- 
1.7.9.5