From e6a595d2db7ad403fcb2b7b168754d7551fc8c9b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Thu, 24 May 2012 21:08:59 +0300
Subject: drm/i915: Reject page flips with changed format/offset/pitch
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Git-commit: e6a595d2db7ad403fcb2b7b168754d7551fc8c9b
Patch-mainline: v3.6-rc1

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>
Acked-by: Michal Srb <msrb@suse.com>
---
 drivers/gpu/drm/i915/intel_display.c |   13 +++++++++++++
 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 4d84fcd..7e31f7a 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;

