[PATCH] drm/udl: limit modes to the sku pixel limits.

[Dave Airlie]

From: Dave Airlie <airlied at redhat.com>

Otherwise when X starts we commonly get a black screen scanning
out nothing, its wierd dpms on/off from userspace brings it back,

With this on F18, multi-seat works again with my 1920x1200 monitor
which is above the sku limit for the device I have.

Cc: stable at vger.kernel.org
Signed-off-by: Dave Airlie <airlied at redhat.com>
---
 drivers/gpu/drm/udl/udl_connector.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/udl/udl_connector.c b/drivers/gpu/drm/udl/udl_connector.c
index ba055e9..8d9dc44 100644
--- a/drivers/gpu/drm/udl/udl_connector.c
+++ b/drivers/gpu/drm/udl/udl_connector.c
@@ -69,6 +69,13 @@ static int udl_get_modes(struct drm_connector *connector)
 static int udl_mode_valid(struct drm_connector *connector,
 			  struct drm_display_mode *mode)
 {
+	struct udl_device *udl = connector->dev->dev_private;
+	if (!udl->sku_pixel_limit)
+		return 0;
+
+	if (mode->vdisplay * mode->hdisplay > udl->sku_pixel_limit)
+		return MODE_VIRTUAL_Y;
+
 	return 0;
 }
 
-- 
1.7.12