From 9851cf5d02703ab60b58a2335481cc195c72ff9c Mon Sep 17 00:00:00 2001

From: Jonathon Jongsma <jjongsma@redhat.com>

Date: Thu, 20 Aug 2015 12:04:32 -0700

Subject: [PATCH] drm/qxl: validate monitors config modes

Due to some recent changes in

drm_helper_probe_single_connector_modes_merge_bits(), old custom modes

were not being pruned properly. In current kernels,

drm_mode_validate_basic() is called to sanity-check each mode in the

list. If the sanity-check passes, the mode's status gets set to to

MODE_OK. In older kernels this check was not done, so old custom modes

would still have a status of MODE_UNVERIFIED at this point, and would

therefore be pruned later in the function.

As a result of this new behavior, the list of modes for a device always

includes every custom mode ever configured for the device, with the

largest one listed first. Since desktop environments usually choose the

first preferred mode when a hotplug event is emitted, this had the

result of making it very difficult for the user to reduce the size of

the display.

The qxl driver did implement the mode_valid connector function, but it

was empty. In order to restore the old behavior where old custom modes

are pruned, we implement a proper mode_valid function for the qxl

driver. This function now checks each mode against the last configured

custom mode and the list of standard modes. If the mode doesn't match

any of these, its status is set to MODE_BAD so that it will be pruned as

expected.

Signed-off-by: Jonathon Jongsma <jjongsma at redhat.com>

Cc: stable at vger.kernel.org

---

 drivers/gpu/drm/qxl/qxl_display.c | 66 ++++++++++++++++++++++++---------------

 drivers/gpu/drm/qxl/qxl_drv.h     |  2 ++

 2 files changed, 42 insertions(+), 26 deletions(-)

diff --git a/drivers/gpu/drm/qxl/qxl_display.c b/drivers/gpu/drm/qxl/qxl_display.c

index a8dbb3ef4e3c..7c6225c84ba6 100644

--- a/drivers/gpu/drm/qxl/qxl_display.c

+++ b/drivers/gpu/drm/qxl/qxl_display.c

@@ -160,9 +160,35 @@ static int qxl_add_monitors_config_modes(struct drm_connector *connector,

 	*pwidth = head->width;

 	*pheight = head->height;

 	drm_mode_probed_add(connector, mode);

+	/* remember the last custom size for mode validation */

+	qdev->monitors_config_width = mode->hdisplay;

+	qdev->monitors_config_height = mode->vdisplay;

 	return 1;

 }

+static struct mode_size {

+	int w;

+	int h;

+} common_modes[] = {

+	{ 640,  480},

+	{ 720,  480},

+	{ 800,  600},

+	{ 848,  480},

+	{1024,  768},

+	{1152,  768},

+	{1280,  720},

+	{1280,  800},

+	{1280,  854},

+	{1280,  960},

+	{1280, 1024},

+	{1440,  900},

+	{1400, 1050},

+	{1680, 1050},

+	{1600, 1200},

+	{1920, 1080},

+	{1920, 1200}

+};

+

 static int qxl_add_common_modes(struct drm_connector *connector,

                                 unsigned pwidth,

                                 unsigned pheight)

@@ -170,29 +196,6 @@ static int qxl_add_common_modes(struct drm_connector *connector,

 	struct drm_device *dev = connector->dev;

 	struct drm_display_mode *mode = NULL;

 	int i;

-	struct mode_size {

-		int w;

-		int h;

-	} common_modes[] = {

-		{ 640,  480},

-		{ 720,  480},

-		{ 800,  600},

-		{ 848,  480},

-		{1024,  768},

-		{1152,  768},

-		{1280,  720},

-		{1280,  800},

-		{1280,  854},

-		{1280,  960},

-		{1280, 1024},

-		{1440,  900},

-		{1400, 1050},

-		{1680, 1050},

-		{1600, 1200},

-		{1920, 1080},

-		{1920, 1200}

-	};

-

 	for (i = 0; i < ARRAY_SIZE(common_modes); i++) {

 		mode = drm_cvt_mode(dev, common_modes[i].w, common_modes[i].h,

 				    60, false, false, false);

@@ -823,11 +826,22 @@ static int qxl_conn_get_modes(struct drm_connector *connector)

 static int qxl_conn_mode_valid(struct drm_connector *connector,

 			       struct drm_display_mode *mode)

 {

+	struct drm_device *ddev = connector->dev;

+	struct qxl_device *qdev = ddev->dev_private;

+	int i;

+

 	/* TODO: is this called for user defined modes? (xrandr --add-mode)

 	 * TODO: check that the mode fits in the framebuffer */

-	DRM_DEBUG("%s: %dx%d status=%d\n", mode->name, mode->hdisplay,

-		  mode->vdisplay, mode->status);

-	return MODE_OK;

+

+	if(qdev->monitors_config_width == mode->hdisplay &&

+	   qdev->monitors_config_height == mode->vdisplay)

+		return MODE_OK;

+

+	for (i = 0; i < ARRAY_SIZE(common_modes); i++) {

+		if (common_modes[i].w == mode->hdisplay && common_modes[i].h == mode->vdisplay)

+			return MODE_OK;

+	}

+	return MODE_BAD;

 }

 static struct drm_encoder *qxl_best_encoder(struct drm_connector *connector)

diff --git a/drivers/gpu/drm/qxl/qxl_drv.h b/drivers/gpu/drm/qxl/qxl_drv.h

index d8549690801d..01a86948eb8c 100644

--- a/drivers/gpu/drm/qxl/qxl_drv.h

+++ b/drivers/gpu/drm/qxl/qxl_drv.h

@@ -325,6 +325,8 @@ struct qxl_device {

 	struct work_struct fb_work;

 	struct drm_property *hotplug_mode_update_property;

+	int monitors_config_width;

+	int monitors_config_height;

 };

 /* forward declaration for QXL_INFO_IO */

-- 

2.4.3