On Friday, June 20, 2008 2:27 pm Jesse Barnes wrote:
> On Friday, June 20, 2008 2:09 pm Jesse Barnes wrote:
> > Michel, can you take a look at this? vblank wait is working really well
> > for me with the latest bits, but I found what I think is a page flip
> > related bug on 965. I've been testing with the attached pre- &
> > post-modeset ioctl patch to the 2D driver. Changing modes, adding &
> > removing outputs and moving a window waiting on vblank events all seem
> > solid & tear free on my 965 (though on 915 we may still have some tearing
> > due to the way interrupts work on that chip, still have to test & fix if
> > necessary).
> >
> > What do you think?
>
> Oops, I've also been testing with this. And looking again at
> c7ee6cc269c26d8e7ed98a16a272eca63daab201 (the "in vblank" handling). I
> think my 965 test machine is fast enough that I haven't seen much tearing
> on it yet, but I think for slower machines we'll definitely need a real
> fix.
>
> My current thinking is that the only non-racy way to handle the "in vblank"
> case is to only use the frame counter to keep the vblank count accurate
> across interrupt disabled periods. While the interrupt is enabled,
> however, the driver should internally keep a counter going based on the
> vblank interrupt and use that to return a value to the core.
>
> If the radeon driver has to do something similar, we could probably just
> update the core drm_handle_vblank() function to use the atomic counter
> instead, which would save a bunch of duplicated driver code... Any
> thoughts there?
Oh, and the patch.
Jesse
diff --git a/shared-core/i915_irq.c b/shared-core/i915_irq.c
index 2287cd0..688a58e 100644
--- a/shared-core/i915_irq.c
+++ b/shared-core/i915_irq.c
@@ -425,13 +425,6 @@ u32 i915_get_vblank_counter(struct drm_device *dev, int plane)
if (i915_in_vblank(dev, pipe))
count++;
#endif
- /* count may be reset by other driver(e.g. 2D driver),
- we have no way to know if it is wrapped or resetted
- when count is zero. do a rough guess.
- */
- if (count == 0 && dev->last_vblank[pipe] < dev->max_vblank_count/2)
- dev->last_vblank[pipe] = 0;
-
return count;
}
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