[Intel-gfx] [PATCH] drm/i915: Emit even number of dwords when emitting LRIs

Damien Lespiau damien.lespiau at intel.com
Wed Oct 22 12:40:30 CEST 2014


On Wed, Oct 22, 2014 at 10:09:49AM +0100, Arun Siluvery wrote:
> The number of DWords should be even when doing ring emits as
> command sequences require QWord alignment.

It looks like we could just pad at the end of the batch instead of one
NOP per register write?

Also, It looks like we could use the LRI variant that can write more
than one register in one go (separate patch)?.

-- 
Damien

> Cc: Mika Kuoppala <mika.kuoppala at intel.com>
> Signed-off-by: Arun Siluvery <arun.siluvery at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_ringbuffer.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index 12a546f..79211ae 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -680,7 +680,7 @@ static int intel_ring_workarounds_emit(struct intel_engine_cs *ring)
>  	if (ret)
>  		return ret;
>  
> -	ret = intel_ring_begin(ring, w->count * 3);
> +	ret = intel_ring_begin(ring, w->count * 4);
>  	if (ret)
>  		return ret;
>  
> @@ -688,6 +688,7 @@ static int intel_ring_workarounds_emit(struct intel_engine_cs *ring)
>  		intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(1));
>  		intel_ring_emit(ring, w->reg[i].addr);
>  		intel_ring_emit(ring, w->reg[i].value);
> +		intel_ring_emit(ring, MI_NOOP);
>  	}
>  
>  	intel_ring_advance(ring);
> -- 
> 2.1.2
> 
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