drm/i915: Reject page flips with changed format/offset/pitch

MI display flips can't handle some changes in the framebuffer
format or layout. Return an error in such cases.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 4d84fcdd413f..7e31f7af0de8 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -6438,6 +6438,19 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
         unsigned long flags;
         int ret;
 
+        /* Can't change pixel format via MI display flips. */
+        if (fb->pixel_format != crtc->fb->pixel_format)
+                return -EINVAL;
+
+        /*
+         * TILEOFF/LINOFF registers can't be changed via MI display flips.
+         * Note that pitch changes could also affect these register.
+         */
+        if (INTEL_INFO(dev)->gen > 3 &&
+            (fb->offsets[0] != crtc->fb->offsets[0] ||
+             fb->pitches[0] != crtc->fb->pitches[0]))
+                return -EINVAL;
+
         work = kzalloc(sizeof *work, GFP_KERNEL);
         if (work == NULL)
                 return -ENOMEM;