From 3b624aa9a9df86dc7d48149e0f18ca223b4355f1 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Tue, 22 Nov 2016 14:48:14 +0100 Subject: [PATCH] randr: rrCheckPixmapBounding: Do not substract crtc non 0 x,y from screen size The purpose of rrCheckPixmapBounding is to make sure that the screen_pixmap is large enough for the slave-output which crtc is being configured. This should include crtc->x and crtc->y, otherwise the crtc might still end up scanning out an area outside of the screen-pixmap. For example: Take a laptop with an external monitor on a slave-output at 1920x1080+0+0 and its internal-screen at 3840x2160+1920+0 and in gnome-settings-daemon move the external monitor to be on the ri ght of the internal screen rather then on the left. First g-s-d will do a RRSetScreenSize to 5760*2160 (which is a nop), then it calls RRSetCrtc to move the slave output to 1920x1080+3840+0, since this is a slave output, rrCheckPixmapBounding gets called, since the 2 crtcs now overlap the code before this commit would shrinks the screen_pixmap to 3180*2160. Then g-s-d calls RRSetCrtc to move the internal screen to 3180*2160+0+0. And we end up with the slave-output configured to scan-out an area which completely falls outside of the screen-pixmap (and end up with a black display on the external monitor). This commit fixes this by not substracting the x1 and y1 coordinates of the union-ed region when determining the new screen_pixmap size. Cc: Nikhil Mahale Cc: Dave Airlie Signed-off-by: Hans de Goede Reviewed-by: Dave Airlie --- randr/rrcrtc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/randr/rrcrtc.c b/randr/rrcrtc.c index 5d404e84b..ac853eab6 100644 --- a/randr/rrcrtc.c +++ b/randr/rrcrtc.c @@ -686,8 +686,8 @@ rrCheckPixmapBounding(ScreenPtr pScreen, } newsize = RegionExtents(&total_region); - new_width = newsize->x2 - newsize->x1; - new_height = newsize->y2 - newsize->y1; + new_width = newsize->x2; + new_height = newsize->y2; if (new_width == screen_pixmap->drawable.width && new_height == screen_pixmap->drawable.height) {