Re: [PATCH 2/2] drm/i915: Add FIXME for bdw semaphore detection in hancheck

[Ben Widawsky <ben@bwidawsk.net>]

On Sat, Mar 15, 2014 at 12:08:56AM +0100, Daniel Vetter wrote:
> Currently not an issue since we don't emit sempahores, but better
> not forget about those.
> 
> As a little prep work extract the ipehr decoding for cleaner control
> flow. And apply a bit of polish.
> 
> Cc: Ben Widawsky <ben@bwidawsk.net>
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Reviewed-by: Ben Widawsky <ben@bwidawsk.net>

I've made a note to add the relevant BDW patch already.

one comment below.
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 20 ++++++++++++++++++--
>  drivers/gpu/drm/i915/i915_reg.h |  3 ++-
>  2 files changed, 20 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 473372a6c97d..0f3a6d791502 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -2525,6 +2525,23 @@ ring_idle(struct intel_ring_buffer *ring, u32 seqno)
>  		i915_seqno_passed(seqno, ring_last_seqno(ring)));
>  }
>  
> +static bool
> +ipehr_is_semaphore_wait(struct drm_device *dev, u32 ipehr)
> +{
> +	if (INTEL_INFO(dev)->gen >= 8) {
> +		/*
> +		 * FIXME: gen8 semaphore support - currently we don't emit
> +		 * semaphores on bdw anyway, but this needs to be addressed when
> +		 * we merge that code.
> +		 */
> +		return false;
> +	} else {

If you wanted to be paranoid:
WARN_ON((ipehr & MI_SEMAPHORE_SYNC_MASK) == MI_SEMAPHORE_SYNC_INVALID)

> +		ipehr &= ~MI_SEMAPHORE_SYNC_MASK;
> +		return ipehr == (MI_SEMAPHORE_MBOX | MI_SEMAPHORE_COMPARE |
> +				 MI_SEMAPHORE_REGISTER);
> +	}
> +}
> +
>  static struct intel_ring_buffer *
>  semaphore_waits_for(struct intel_ring_buffer *ring, u32 *seqno)
>  {
> @@ -2533,8 +2550,7 @@ semaphore_waits_for(struct intel_ring_buffer *ring, u32 *seqno)
>  	int i;
>  
>  	ipehr = I915_READ(RING_IPEHR(ring->mmio_base));
> -	if ((ipehr & ~(0x3 << 16)) !=
> -	    (MI_SEMAPHORE_MBOX | MI_SEMAPHORE_COMPARE | MI_SEMAPHORE_REGISTER))
> +	if (!ipehr_is_semaphore_wait(ring->dev, ipehr))
>  		return NULL;
>  
>  	/*
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 146609ab42bb..23267859156f 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -244,7 +244,8 @@
>  #define   MI_SEMAPHORE_SYNC_BVE	    (0<<16) /* VECS wait for BCS  (VEBSYNC) */
>  #define   MI_SEMAPHORE_SYNC_VVE	    (1<<16) /* VECS wait for VCS  (VEVSYNC) */
>  #define   MI_SEMAPHORE_SYNC_RVE	    (2<<16) /* VECS wait for RCS  (VERSYNC) */
> -#define   MI_SEMAPHORE_SYNC_INVALID  (3<<16)
> +#define   MI_SEMAPHORE_SYNC_INVALID (3<<16)
> +#define   MI_SEMAPHORE_SYNC_MASK    (3<<16)
>  #define MI_SET_CONTEXT		MI_INSTR(0x18, 0)
>  #define   MI_MM_SPACE_GTT		(1<<8)
>  #define   MI_MM_SPACE_PHYSICAL		(0<<8)
> -- 
> 1.8.1.4
> 

-- 
Ben Widawsky, Intel Open Source Technology Center