drm/fb-helper: Allow var->x/yres(_virtual) < fb->width/height again

Otherwise this can also prevent modesets e.g. for switching VTs, when
multiple monitors with different native resolutions are connected.

The depths must match though, so keep the != test for that.

Also update the DRM_DEBUG output to be slightly more accurate, this
doesn't only affect requests from userspace.

Bugzilla: https://bugs.freedesktop.org/99841
Fixes: 865afb1 ("drm/fb-helper: reject any changes to the fbdev")
Signed-off-by: Michel Dänzer <[email protected]>
Reviewed-by: Daniel Stone <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: Michel Dänzer

drivers/gpu/drm/drm_fb_helper.c

@@ -1260,9 +1260,9 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
 	 * to KMS, hence fail if different settings are requested.
 	 */
 	if (var->bits_per_pixel != fb->format->cpp[0] * 8 ||
-	    var->xres != fb->width || var->yres != fb->height ||
-	    var->xres_virtual != fb->width || var->yres_virtual != fb->height) {
-		DRM_DEBUG("fb userspace requested width/height/bpp different than current fb "
+	    var->xres > fb->width || var->yres > fb->height ||
+	    var->xres_virtual > fb->width || var->yres_virtual > fb->height) {
+		DRM_DEBUG("fb requested width/height/bpp can't fit in current fb "
 			  "request %dx%d-%d (virtual %dx%d) > %dx%d-%d\n",
 			  var->xres, var->yres, var->bits_per_pixel,
 			  var->xres_virtual, var->yres_virtual,