Re: [PATCH] drm/radeon: Move pageflip request from vblank IRQ to ioctl

[Simon Farnsworth <simon.farnsworth@onelan.co.uk>]

On Wednesday 6 July 2011, Jerome Glisse <j.glisse@gmail.com> wrote:
> On Wed, Jul 6, 2011 at 12:29 PM, Simon Farnsworth
> 
> > In particular, I'm a bit hazy about what the fence in pageflip is
> > doing - I assume it's there to synchronize drawing and scanout, so
> > that I don't flip to a buffer that's still being drawn on by the GPU.
> > 
> In my view all the fence stuff become useless as when the irq handler
> call we know we can unpin previous scanout (the crtc is scanning from
> new buffer). Otherwise it looks good (beside the optimization of
> computing how much time we should sleep instead of while msleep but
> this can be left as a latter patch).
> 
So, I don't know why this makes a difference - but removing the fence 
completely causes the second pageflip to stall forever. Changing it for a 
radeon_bo_wait on the new frontbuffer still results in infinite stalls.

I've noticed a couple of minor issues in the patch anyway (a redundant 
lock/unlock pair left in, and I should be using usleep_range not msleep, given 
that I want to wait for less than a millisecond normally), so I'll respin 
anyway.
-- 
Simon Farnsworth
Software Engineer
ONELAN Limited
http://www.onelan.com/