On Wed, 4 Aug 2010 21:22:10 +0200, Daniel Vetter <daniel.vet...@ffwll.ch>
wrote:
> My i855GM suffers from a 80k/s interrupt storm without this.
> So add 2nd gen to the list of things that don't like more than
> one outstanding pageflip request.
>
> Furthermore I've changed the busy loop into a ringbuffer wait.
> Busy-loops that don't check whether the chip died are simply evil.
> And performance should actually improve, because there's usually
> a decent amount of rendering queued on the gpu, hopefully rendering
> that MI_WAIT into a noop by the time it's executed.
>
> The current code holds dev->struct_mutex while executing this loop,
> hence stalling all other gem activity anyway.
>
> Signed-off-by: Daniel Vetter <daniel.vet...@ffwll.ch>
> Cc: sta...@kernel.org
> ---
> drivers/gpu/drm/i915/intel_display.c | 13 ++++++++-----
> 1 files changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c
> b/drivers/gpu/drm/i915/intel_display.c
> index 8135ee0..7b6035e 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -4916,14 +4916,17 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
> work->pending_flip_obj = obj;
>
> if (intel_crtc->plane)
> - flip_mask = I915_DISPLAY_PLANE_B_FLIP_PENDING_INTERRUPT;
> + flip_mask = MI_WAIT_FOR_PLANE_B_FLIP;
> else
> - flip_mask = I915_DISPLAY_PLANE_A_FLIP_PENDING_INTERRUPT;
> + flip_mask = MI_WAIT_FOR_PLANE_A_FLIP;
>
> /* Wait for any previous flip to finish */
> - if (IS_GEN3(dev))
> - while (I915_READ(ISR) & flip_mask)
> - ;
> + if (IS_GEN3(dev) || IS_GEN2(dev)) {
> + BEGIN_LP_RING(2);
> + OUT_RING(MI_WAIT_FOR_EVENT | flip_mask);
> + OUT_RING(0);
> + ADVANCE_LP_RING();
> + }
If you move the if(intel_crtc->plane) inside the gen2/3 block, then I'll
test it on my netbooks. :)
Starting to look like intel_overlay.c ;-)
--
Chris Wilson, Intel Open Source Technology Centre
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