Bogus video resolution in Linux 3.5-rc4

After upgrading to Linux 3.5-rc4 from 3.4.4, I noticed that my monitor switched to a resolution of 1280x960 rather than the native 1280x1024, and nouveau has set up a framebuffer of 1680x945. It goes without saying that the result looks terrible.

Bisecting shows that the problem started with commit cb21aafe1:

--8<---------------cut here---------------start------------->8--- commit cb21aafe121b1c3ad4c77cc5c22320163f16ba42

Author: Adam Jackson <[email protected]>
Date:   Fri Apr 13 16:33:36 2012 -0400

drm/edid: Do drm_dmt_modes_for_range() for all range descriptor types

EDID 1.4 retcons the meaning of the "GTF feature" bit to mean "is continuous frequency", and moves the set of supported timing formulas into the range descriptor itself. In any event, the range descriptor can act as a filter on the DMT list without regard to a specific timing formula.

Signed-off-by Adam Jackson <[email protected]>

Tested-by Takashi Iwai <[email protected]>

Reviewed-by Rodrigo Vivi <[email protected]>

Signed-off-by Dave Airlie <[email protected]>

drivers/gpu/drm/drm_edid.c +6 -6

index cb40611..9363349 100644
@@ -1042,12 +1042,13 @@ do_inferred_modes(struct detailed_timing *timing, void *c)
 {
 	struct detailed_mode_closure *closure = c;
 	struct detailed_non_pixel *data = &timing->data.other_data;
-	int gtf = (closure->edid->features & DRM_EDID_FEATURE_DEFAULT_GTF);
 
-	if (gtf && data->type == EDID_DETAIL_MONITOR_RANGE)
-		closure->modes += drm_dmt_modes_for_range(closure->connector,
-							  closure->edid,
-							  timing);
+	if (data->type != EDID_DETAIL_MONITOR_RANGE)
+		return;
+
+	closure->modes += drm_dmt_modes_for_range(closure->connector,
+						  closure->edid,
+						  timing);
 }
 
 static int
--8<---------------cut here---------------end--------------->8---

With a kernel from this commit nouveau sets up a resolution of 1400x1050; kernels built from commits cffd754 and fc48f16 complain about an invalid EDID and use the 1024x768 fallback.

Attached is the /sys/class/drm/card0-DVI-I-1/edid file from a working kernel; in 3.5-rc4 it is identical.

And, does the patch below help?

Takashi

---

drivers/gpu/drm/drm_edid.c +4 -1

index 5873e48..dab8580 100644
@@ -116,6 +116,7 @@ static struct edid_quirk {
 
 	/* Proview AY765C */
 	{ "PTS", 765, EDID_QUIRK_FIRST_DETAILED_PREFERRED },
+	{ "PTS", 793, EDID_QUIRK_FIRST_DETAILED_PREFERRED },
 
 	/* Samsung SyncMaster 205BW.  Note: irony */
 	{ "SAM", 541, EDID_QUIRK_DETAILED_SYNC_PP },

@@ -1404,7 +1405,9 @@ do_detailed_mode(struct detailed_timing *timing, void *c)
 		if (!newmode)
 			return;
 
-		if (closure->preferred)
+		if (closure->preferred ||
+		    ((closure->quirks & EDID_QUIRK_FIRST_DETAILED_PREFERRED) &&
+		     !closure->modes))
 			newmode->type |= DRM_MODE_TYPE_PREFERRED;
 
 		drm_mode_probed_add(closure->connector, newmode);

Looking at the EDID data, the problem is likely that your monitor doesn't give the proper preferred mode.
What does xrandr output show?

And, does the patch below help?

---

drivers/gpu/drm/drm_edid.c +4 -1

index 5873e48..dab8580 100644
@@ -116,6 +116,7 @@ static struct edid_quirk {
 
 	/* Proview AY765C */
 	{ "PTS", 765, EDID_QUIRK_FIRST_DETAILED_PREFERRED },
+	{ "PTS", 793, EDID_QUIRK_FIRST_DETAILED_PREFERRED },
 
 	/* Samsung SyncMaster 205BW.  Note: irony */
 	{ "SAM", 541, EDID_QUIRK_DETAILED_SYNC_PP },

@@ -1404,7 +1405,9 @@ do_detailed_mode(struct detailed_timing *timing, void *c)
 		if (!newmode)
 			return;
 
-		if (closure->preferred)
+		if (closure->preferred ||
+		    ((closure->quirks & EDID_QUIRK_FIRST_DETAILED_PREFERRED) &&
+		     !closure->modes))
 			newmode->type |= DRM_MODE_TYPE_PREFERRED;
 
 		drm_mode_probed_add(closure->connector, newmode);

Quoted 1 line

And, does the patch below help?

Somewhat: at least I get 1280x1024 again, but at 60 rather than 75 Hz.

The xrandr command shows various bogus modes.

Am 25.06.2012 um 17:53 schrieb Takashi Iwai:

Quoted 3 lines

Looking at the EDID data, the problem is likely that your monitor doesn't give the proper preferred mode.
What does xrandr output show?

,----

| Screen 0: minimum 320 x 200, current 1280 x 1024, maximum 8192 x 8192
| DVI-I-1 connected 1280x1024+0+0 (normal left inverted right x axis y axis) 376mm x 301mm
|    1280x1024      75.0*    60.0  
|    1024x768       75.1     75.0     70.1     60.0  
|    832x624        74.6  
|    800x600        72.2     75.0     60.3     56.2  
|    640x480        72.8     75.0     66.7     60.0     59.9  
| VGA-1 disconnected (normal left inverted right x axis y axis)

`----

I should note that the monitor is actually connected via VGA, not DVI. This seems to be similar to https://bugs.freedesktop.org/50830, but since it never caused any real problems for me, I didn't bother.

Quoted 1 line

And, does the patch below help?

Somewhat: at least I get 1280x1024 again, but at 60 rather than 75 Hz.

The xrandr command shows various bogus modes.

,----

| Screen 0: minimum 320 x 200, current 1280 x 1024, maximum 8192 x 8192
| DVI-I-1 connected 1280x1024+0+0 (normal left inverted right x axis y axis) 376mm x 301mm
|    1280x1024      60.0*+   75.0  
|    1680x945       60.0  
|    1400x1050      60.0  
|    1600x900       60.0  
|    1440x900       75.0     59.9  
|    1280x960       60.0  
|    1366x768       60.0  
|    1360x768       60.0  
|    1280x800       74.9     59.8  
|    1152x864       75.0  
|    1280x768       74.9     59.9  
|    1024x768       75.1     75.0     70.1     60.0  
|    1024x576       60.0  
|    832x624        74.6  
|    800x600        72.2     75.0     60.3     56.2  
|    848x480        60.0  
|    640x480        75.0     72.8     72.8     66.7     60.0     59.9  
| VGA-1 disconnected (normal left inverted right x axis y axis)

`----

Cheers,
Sven

Quoted 24 lines

---

drivers/gpu/drm/drm_edid.c +4 -1

index 5873e48..dab8580 100644
@@ -116,6 +116,7 @@ static struct edid_quirk {
 
 	/* Proview AY765C */
 	{ "PTS", 765, EDID_QUIRK_FIRST_DETAILED_PREFERRED },
+	{ "PTS", 793, EDID_QUIRK_FIRST_DETAILED_PREFERRED },
 
 	/* Samsung SyncMaster 205BW.  Note: irony */
 	{ "SAM", 541, EDID_QUIRK_DETAILED_SYNC_PP },

@@ -1404,7 +1405,9 @@ do_detailed_mode(struct detailed_timing *timing, void *c)
 		if (!newmode)
 			return;
 
-		if (closure->preferred)
+		if (closure->preferred ||
+		    ((closure->quirks & EDID_QUIRK_FIRST_DETAILED_PREFERRED) &&
+		     !closure->modes))
 			newmode->type |= DRM_MODE_TYPE_PREFERRED;
 
 		drm_mode_probed_add(closure->connector, newmode);

Quoted 3 lines

Quoted 1 line

And, does the patch below help?

Somewhat: at least I get 1280x1024 again, but at 60 rather than 75 Hz.

I guess it worked casually because 1280x1024@75 was the highest resolution / rate, so it was picked up as the preferred mode...

Quoted 1 line

The xrandr command shows various bogus modes.

Can't these values be displayed on your monitor at all?

Am 25.06.2012 um 21:24 schrieb Takashi Iwai:

Quoted 6 lines

Quoted 3 lines

Quoted 1 line

And, does the patch below help?

Somewhat: at least I get 1280x1024 again, but at 60 rather than 75 Hz.

I guess it worked casually because 1280x1024@75 was the highest resolution / rate, so it was picked up as the preferred mode...

Quite possible. Problem is that 1280x1024@60 looks worse, so I'd like to get the 75 Hz back.

Quoted 3 lines

Quoted 1 line

The xrandr command shows various bogus modes.

Can't these values be displayed on your monitor at all?

It's a TFT LCD with 1280x1024 pixels.

At Mon, 25 Jun 2012 21:38:56 +0200,

Quoted 10 lines · Sven Joachim

Am 25.06.2012 um 21:24 schrieb Takashi Iwai:

Quoted 6 lines

Quoted 3 lines

Quoted 1 line

And, does the patch below help?

Somewhat: at least I get 1280x1024 again, but at 60 rather than 75 Hz.

I guess it worked casually because 1280x1024@75 was the highest resolution / rate, so it was picked up as the preferred mode...

Quoted 8 lines

Quite possible. Problem is that 1280x1024@60 looks worse, so I'd like to get the 75 Hz back.

Quoted 3 lines

Quoted 1 line

The xrandr command shows various bogus modes.

Can't these values be displayed on your monitor at all?

It's a TFT LCD with 1280x1024 pixels.

Yes, but displaying higher resolutions wasn't too uncommon in the earlier VGA days. So, this doesn't mean the higher modes are "bogus" as long they are in the range the monitor itself advertises.

On the second thought, if there are many such broken monitors, it might be safer to exclude the inferred modes with higher resolutions.

The original problem was that the resolution like 1366x768 or 1600x900 doesn't appear in the mode list. These are supposed to be lower than the native. Restricting the higher resolutions won't regress for these problems.

The patch below is a quick fix.

Takashi

---
From: Takashi Iwai <[email protected]>
Subject: [PATCH] drm: edid: Don't add inferred modes with higher resolution

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.

Signed-off-by Takashi Iwai <[email protected]>

---
 drivers/gpu/drm/drm_edid.c |   27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

drivers/gpu/drm/drm_edid.c +22 -2

index 5873e48..a8743c3 100644
@@ -1039,6 +1039,24 @@ 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;
+}
+
 static int
 drm_dmt_modes_for_range(struct drm_connector *connector, struct edid *edid,
 			struct detailed_timing *timing)

@@ -1048,7 +1066,8 @@ 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);

@@ -1088,7 +1107,8 @@ drm_gtf_modes_for_range(struct drm_connector *connector, struct edid *edid,
 			return modes;
 
 		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;
 		}

Quoted 108 lines · Takashi Iwai

At Mon, 25 Jun 2012 21:38:56 +0200,

Quoted 10 lines · Sven Joachim

Am 25.06.2012 um 21:24 schrieb Takashi Iwai:

Quoted 6 lines

Quoted 3 lines

Quoted 1 line

And, does the patch below help?

Somewhat: at least I get 1280x1024 again, but at 60 rather than 75 Hz.

I guess it worked casually because 1280x1024@75 was the highest resolution / rate, so it was picked up as the preferred mode...

Quoted 8 lines

Quite possible. Problem is that 1280x1024@60 looks worse, so I'd like to get the 75 Hz back.

Quoted 3 lines

Quoted 1 line

The xrandr command shows various bogus modes.

Can't these values be displayed on your monitor at all?

It's a TFT LCD with 1280x1024 pixels.

Yes, but displaying higher resolutions wasn't too uncommon in the earlier VGA days. So, this doesn't mean the higher modes are "bogus" as long they are in the range the monitor itself advertises.

On the second thought, if there are many such broken monitors, it might be safer to exclude the inferred modes with higher resolutions.

The original problem was that the resolution like 1366x768 or 1600x900 doesn't appear in the mode list. These are supposed to be lower than the native. Restricting the higher resolutions won't regress for these problems.

The patch below is a quick fix.

Takashi

---
From: Takashi Iwai <[email protected]>
Subject: [PATCH] drm: edid: Don't add inferred modes with higher resolution

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.

Signed-off-by Takashi Iwai <[email protected]>

---
 drivers/gpu/drm/drm_edid.c |   27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

drivers/gpu/drm/drm_edid.c +22 -2

index 5873e48..a8743c3 100644
@@ -1039,6 +1039,24 @@ 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;
+}
+
 static int
 drm_dmt_modes_for_range(struct drm_connector *connector, struct edid *edid,
 			struct detailed_timing *timing)

@@ -1048,7 +1066,8 @@ 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);

@@ -1088,7 +1107,8 @@ drm_gtf_modes_for_range(struct drm_connector *connector, struct edid *edid,
 			return modes;
 
 		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;
 		}

drivers/gpu/drm/drm_edid.c drm_cvt_modes_for_range(struct drm_connector *connector, struct edid *edid, · line 1143

Quoted 9 lines

drivers/gpu/drm/drm_edid.c +2 -1

@@ -1116,7 +1136,8 @@ drm_cvt_modes_for_range(struct drm_connector *connector, struct edid *edid,
 			return modes;
 
 		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;
 		}

Hello all,

I had the exact same problem as Sven, bisected to cb21aafe121b1c3ad4c77cc5c22320163f16ba42. Takashi's patch (supra) fixes the issue for me.

I had the exact same problem as Sven, bisected to cb21aafe121b1c3ad4c77cc5c22320163f16ba42. Takashi's patch (supra) fixes the issue for me.

From: Takashi Iwai <[email protected]>
Subject: [PATCH] drm: edid: Don't add inferred modes with higher resolution

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.

Quoted 10 lines · Takashi Iwai

From: Takashi Iwai <[email protected]>
Subject: [PATCH] drm: edid: Don't add inferred modes with higher resolution

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.

Quoted 3 lines

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.

This is a little aggressive on CRTs, but whatever, better than what's there.

Reviewed-by Adam Jackson <[email protected]>

Quoted 1 line

The xrandr command shows various bogus modes.

Can't these values be displayed on your monitor at all? If they can be displayed, they are valid modes, not really bogus. After all, they are values that EDID of your montor advertises as available ranges.

HDMI TV - lots of new modes but it already advertised all the CVT that it supports and all the new are bogus.