drm/i915/fbc: disable framebuffer compression on GeminiLake

On many (all?) the Gemini Lake systems we work with, there is frequent
momentary graphical corruption at the top of the screen, and it seems
that disabling framebuffer compression can avoid this.

The ticket was reported 6 months ago and has already affected a
multitude of users, without any real progress being made. So, lets
disable framebuffer compression on GeminiLake until a solution is found.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108085
Fixes: fd7d6c5c ("drm/i915: enable FBC on gen9+ too")
Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: <stable@vger.kernel.org> # v4.11+
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Drake <drake@endlessm.com>
Signed-off-by: Jian-Hong Pan <jian-hong@endlessm.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190423092810.28359-1-jian-hong@endlessm.com

drivers/gpu/drm/i915/intel_fbc.c

@@ -1280,6 +1280,10 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *dev_priv)
 	if (!HAS_FBC(dev_priv))
 		return 0;
 
+	/* https://bugs.freedesktop.org/show_bug.cgi?id=108085 */
+	if (IS_GEMINILAKE(dev_priv))
+		return 0;
+
 	if (IS_BROADWELL(dev_priv) || INTEL_GEN(dev_priv) >= 9)
 		return 1;