[PATCH] drm/i915: Discard BIOS framebuffers too small to accommodate chosen mode

Chris Wilson
2014-04-23T07:39:43Z

If the inherited BIOS framebuffer is smaller than the mode selected for
fbdev, then if we continue to use it then we cause display corruption as
we do not setup the panel fitter to upscale.

Regression from commit d978ef14456a38034f6c0e94a794129501f89200
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date: Fri Mar 7 08:57:51 2014 -0800

drm/i915: Wrap the preallocated BIOS framebuffer and preserve for KMS fbcon v12

v2: Add a debug message to track the discard of the BIOS fb.

Reported-by: Knut Petersen <Knut_Petersen@t-online.de>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=77767
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
---
drivers/gpu/drm/i915/intel_fbdev.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_fbdev.c b/drivers/gpu/drm/i915/intel_fbdev.c
index b16116db6c37..dbd3f7ce6354 100644
--- a/drivers/gpu/drm/i915/intel_fbdev.c
+++ b/drivers/gpu/drm/i915/intel_fbdev.c
@@ -133,6 +133,16 @@ static int intelfb_create(struct drm_fb_helper *helper,

mutex_lock(&dev->struct_mutex);

+ if (intel_fb &&
+ (sizes->fb_width > intel_fb->base.width ||
+ sizes->fb_height > intel_fb->base.height)) {
+ DRM_DEBUG_KMS("BIOS fb too small (%dx%d), we require (%dx%d),"
+ " releasing it\n",
+ intel_fb->base.width, intel_fb->base.height,
+ sizes->fb_width, sizes->fb_height);
+ drm_framebuffer_reference(&ifbdev->fb->base);
+ intel_fb = ifbdev->fb = NULL;
+ }
if (!intel_fb || WARN_ON(!intel_fb->obj)) {
DRM_DEBUG_KMS("no BIOS fb, allocating a new one\n");
ret = intelfb_alloc(helper, sizes);
--
1.9.2