On Tue, Aug 3, 2021 at 4:34 AM Michel Dänzer michel@daenzer.net wrote:
On 2021-08-02 4:51 p.m., Alex Deucher wrote:
On Mon, Aug 2, 2021 at 4:31 AM Daniel Vetter daniel@ffwll.ch wrote:
On Mon, Aug 02, 2021 at 10:12:47AM +0200, Christian König wrote:
Am 02.08.21 um 09:43 schrieb Zhenneng Li:
When primary bo is updated, crtc's pitch may have not been updated, this will lead to show disorder content when user changes display mode, we update crtc's pitch in page flip to avoid this bug. This refers to amdgpu's pageflip.
Alex is the expert to ask about that code, but I'm not sure if that is really correct for the old hardware.
As far as I know the crtc's pitch should not change during a page flip, but only during a full mode set.
So could you elaborate a bit more how you trigger this?
legacy page_flip ioctl only verifies that the fb->format stays the same. It doesn't check anything else (afair never has), this is all up to drivers to verify.
Personally I'd say add a check to reject this, since testing this and making sure it really works everywhere is probably a bit much on this old hw.
If just the pitch changed, that probably wouldn't be much of a problem, but if the pitch is changing, that probably implies other stuff has changed as well and we'll just be chasing changes. I agree it would be best to just reject anything other than updating the scanout address.
FWIW, that means page flipping cannot be used in some cases which work fine by changing the pitch, which can result in tearing: https://gitlab.freedesktop.org/xorg/xserver/-/issues/839 (which says the i915 driver handles this as well).
Ok. In that case, @Zhenneng can you update all of the pitch in all of the page_flip functions in radeon rather than just the evergreen one?
Thanks,
Alex
-- Earthling Michel Dänzer | https://redhat.com Libre software enthusiast | Mesa and X developer