[Intel-gfx] [PATCH 05/10] drm/i915: Disable 'get seqno' workaround for VLV

[Daniel Vetter]

On Tue, Dec 09, 2014 at 12:59:08PM +0000, John.C.Harrison at Intel.com wrote:
> From: Dave Gordon <david.s.gordon at intel.com>
> 
> There is a workaround for a hardware bug when reading the seqno from the status
> page. The bug does not exist on VLV however, the workaround was still being
> applied.

Given how much trouble the missed seqno fun cause us I'd like more
justification. What kind of (stress)-testing has been done here? And
you're sure you've never seen the little dmesg notice that the kernel
switched to polling?
-Daniel

> 
> Change-Id: Ic781fdb31e1f794ce1fa8a6d0d5ee379756c5db6
> Signed-off-by: Dave Gordon <david.s.gordon at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_ringbuffer.c |    5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 3887f1a..f990ce4 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -2367,7 +2367,10 @@ int intel_init_render_ring_buffer(struct drm_device *dev)
>  		ring->irq_get = gen6_ring_get_irq;
>  		ring->irq_put = gen6_ring_put_irq;
>  		ring->irq_enable_mask = GT_RENDER_USER_INTERRUPT;
> -		ring->get_seqno = gen6_ring_get_seqno;
> +		if (IS_VALLEYVIEW(dev))
> +			ring->get_seqno = ring_get_seqno;
> +		else
> +			ring->get_seqno = gen6_ring_get_seqno;
>  		ring->set_seqno = ring_set_seqno;
>  		if (i915_semaphore_is_enabled(dev)) {
>  			ring->semaphore.sync_to = gen6_ring_sync;
> -- 
> 1.7.9.5
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch