Re: [PATCH 21/23] drm/i915/gen9: Set fbc watermarks disabled

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

On Thu, May 26, 2016 at 06:29:44PM +0300, Mika Kuoppala wrote:
> According to bspec this prevents screen corruption when fbc is
> used.
> 
> References: HSD#2135555, HSD#2137270
> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 262180c0ba70..62734a16e873 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -67,6 +67,9 @@ static void gen9_init_clock_gating(struct drm_device *dev)
>  
>  	I915_WRITE(GEN8_CHICKEN_DCPR_1,
>  		   I915_READ(GEN8_CHICKEN_DCPR_1) | MASK_WAKEMEM);
> +
> +	I915_WRITE(DISP_ARB_CTL,
> +		   I915_READ(DISP_ARB_CTL) | DISP_FBC_WM_DIS);

Hmm I thought that FBC WM doesn't exist anymore on SKL+. I'm pretty sure
we don't have any code for it at least.

>  }
>  
>  static void bxt_init_clock_gating(struct drm_device *dev)
> @@ -2798,7 +2801,7 @@ static void ilk_write_wm_values(struct drm_i915_private *dev_priv,
>  
>  	if (dirty & WM_DIRTY_FBC) {
>  		val = I915_READ(DISP_ARB_CTL);
> -		if (results->enable_fbc_wm)
> +		if (!IS_GEN9(dev) && results->enable_fbc_wm)

That code won't even run SKL+.

>  			val &= ~DISP_FBC_WM_DIS;
>  		else
>  			val |= DISP_FBC_WM_DIS;
> -- 
> 2.5.0
> 
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-- 
Ville Syrjälä
Intel OTC
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