On 12/10/2014 04:53 PM, Ville Syrjälä wrote:
On Wed, Dec 10, 2014 at 02:53:01PM +0100, Daniel Vetter wrote:
On Wed, Dec 10, 2014 at 11:13:28AM +0000, Chris Wilson wrote:
On Wed, Dec 10, 2014 at 11:23:44AM +0100, Daniel Vetter wrote:
On Wed, Dec 10, 2014 at 08:17:11AM +0000, Chris Wilson wrote:
This added as a BUG_ON as it considered that no one would ever request
an unaligned object. However, it turns out that some BIOSes will
allocate a scanout that is offset from 0 and not aligned to a page
boundary, and we were passing this through and hitting the BUG_ON during
boot.
Quietly reject such a request to reserve the unaligned stolen object and
let the boot continue, restoring previous behaviour (i.e. no BIOS
framebuffer preservation).
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=86883
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
drivers/gpu/drm/i915/i915_gem_stolen.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index 5c616ec2c5c8..a3bc0fa07c6c 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -646,13 +646,15 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
DRM_DEBUG_KMS("creating preallocated stolen object: stolen_offset=%x, gtt_offset=%x, size=%x\n",
stolen_offset, gtt_offset, size);
- /* KISS and expect everything to be page-aligned */
- BUG_ON(stolen_offset & 4095);
- BUG_ON(size & 4095);
-
if (WARN_ON(size == 0))
return NULL;
+ /* KISS and expect everything to be GTT page-aligned */
+ if ((stolen_offset | size) & 4095) {
Imo we should stil WARN_ON and fixup up the takeover code to align things
properly ...
You shot down my idea for storing deltas into objects in the past...
The BIOS scanout is properly aligned to the rules of the display engine,
just not according to our mm restrictions. The bigger question is
whether our 1:1 offset-to-stolen mapping is correct. It could well be
that that the framebuffer is at stolen address 0, but just has a GTT
offset.
So the only question is whether we reject the object reservation at the
stolen layer or at the plane config layer. I decided that stolen was
better, because it is failing to meet our mm restrictions not
hardware restrictions.
The framebuffer layer can very much cope with offsets, so no need to
reject it. We just need to patch up the framebuffer we create a bit.
Offsets are in pixels but that should align well.
Or someone can dig out my old fb->offsets[] handling patch (and double check
that it's sane, fixing if not).
http://lists.freedesktop.org/archives/intel-gfx/2012-May/017584.html
Is it that one?
Thanks,
Ander
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