Re: [PATCH 3/6] drm/i915/vlv: Modified the programming of 2 regs in Ring initialisation

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Jan 22, 2014 at 09:15:07AM +0530, akash.goel@intel.com wrote:
> From: Akash Goel <akash.goel@intel.com>
> 
> Modified programming of following 2 regs in Render ring initialisation fn.
> 1. GFX_MODE_GEN7 (Enabling TLB invalidate)
> 2. MI_MODE (Enabling MI Flush)
> 
> Signed-off-by: Akash Goel <akash.goel@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_ringbuffer.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index e8ec536..8b99df2 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -563,7 +563,9 @@ static int init_render_ring(struct intel_ring_buffer *ring)
>  	int ret = init_ring_common(ring);
>  
>  	if (INTEL_INFO(dev)->gen > 3)
> -		I915_WRITE(MI_MODE, _MASKED_BIT_ENABLE(VS_TIMER_DISPATCH));
> +		if (!IS_VALLEYVIEW(dev))
> +			I915_WRITE(MI_MODE,
> +				_MASKED_BIT_ENABLE(VS_TIMER_DISPATCH));

BSpec says this should be enabled for everything before IVB. So based on
that the condition should just be 'if (gen > 3 && gen < 7)'

>  
>  	/* We need to disable the AsyncFlip performance optimisations in order
>  	 * to use MI_WAIT_FOR_EVENT within the CS. It should already be
> @@ -579,10 +581,17 @@ static int init_render_ring(struct intel_ring_buffer *ring)
>  		I915_WRITE(GFX_MODE,
>  			   _MASKED_BIT_ENABLE(GFX_TLB_INVALIDATE_ALWAYS));
>  
> -	if (IS_GEN7(dev))
> -		I915_WRITE(GFX_MODE_GEN7,
> -			   _MASKED_BIT_DISABLE(GFX_TLB_INVALIDATE_ALWAYS) |
> -			   _MASKED_BIT_ENABLE(GFX_REPLAY_MODE));
> +	if (IS_GEN7(dev)) {
> +		if (IS_VALLEYVIEW(dev)) {
> +			I915_WRITE(GFX_MODE_GEN7,
> +				_MASKED_BIT_ENABLE(GFX_REPLAY_MODE));
> +			I915_WRITE(MI_MODE, I915_READ(MI_MODE) |
> +				_MASKED_BIT_ENABLE(MI_FLUSH_ENABLE));

Why do we need to enable MI_FLUSH, and why only for VLV?

> +		} else
> +			I915_WRITE(GFX_MODE_GEN7,
> +				_MASKED_BIT_DISABLE(GFX_TLB_INVALIDATE_ALWAYS) |
> +				_MASKED_BIT_ENABLE(GFX_REPLAY_MODE));
> +	}

According to BSpec the GFX_TLB_INVALIDATE_ALWAYS bit only exists on SNB.
So it would we should just drop it here.

>  
>  	if (INTEL_INFO(dev)->gen >= 5) {
>  		ret = init_pipe_control(ring);
> -- 
> 1.8.5.2
> 
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-- 
Ville Syrjälä
Intel OTC