[Intel-gfx] [PATCH 2/2] drm/i915/dgfx: Do not write in removed FBC fence registers

[Ville Syrjälä]

On Tue, Jan 28, 2020 at 03:52:41PM -0800, José Roberto de Souza wrote:
> From: Radhakrishna Sripada <radhakrishna.sripada at intel.com>
> 
> dgfx platforms do not support CPU fence and FBC host tracking so
> lets avoid write to removed registers.
> 
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Matt Roper <matthew.d.roper at intel.com>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada at intel.com>
> Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_fbc.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
> index 1f0d24a1dec1..12900b8ce28e 100644
> --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> @@ -314,7 +314,12 @@ static void gen7_fbc_activate(struct drm_i915_private *dev_priv)
>  		break;
>  	}
>  
> -	if (params->fence_id >= 0) {
> +	if (IS_DGFX(dev_priv)) {
> +		/*
> +		 * dGFX GPUs don't have apperture or fences and only rely on FBC
> +		 * render nuke to track frontbuffer modifications
> +		 */
> +	} else if (params->fence_id >= 0) {
>  		dpfc_ctl |= IVB_DPFC_CTL_FENCE_EN;
>  		intel_de_write(dev_priv, SNB_DPFC_CTL_SA,
>  			       SNB_CPU_FENCE_ENABLE | params->fence_id);

if (fence) {
	do stuff
} else if (num_fences) {
	do other stuff
}

> -- 
> 2.25.0
> 
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-- 
Ville Syrjälä
Intel