Re: [PATCH] drm/i915: Fix current fb blocking for page flip.

[Chris Wilson <chris@chris-wilson.co.uk>]

On Thu, 21 Oct 2010 17:55:13 +0800, Chia-I Wu <olvaffe@gmail.com> wrote:
> Hi list,
> 
> According to the doc for page_flip, intel_crtc_page_flip should
> 
>    ... block all rendering to the current fb until the flip has
>    completed.
> 
> I am not entirely sure, but it seems that it is
> work->old_fb_obj->pending_flip that needs to be incremented instead of
> work->pending_flip_obj->pending_flip.  This patch does fix the
> rendering artifacts with my Android on i915 project.  Any thought?

My understanding is that we want to block any attempts to render to the
new back-buffer, i.e. the current front-buffer, until the flip has
occurred. Following that logic we need to increment pending flip on the
existing fb, which at first glance is indeed the fix you propose.

Jesse, Kirstian, thoughts?
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre