[Intel-gfx] [PATCH 1/2] drm/i915: Always use cpp==4 for FW_BLC_SELF on 915GM/945GM

[Chris Wilson]

On Fri, Jul 29, 2016 at 05:57:01PM +0300, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Bspec says:
> "FW_BLC_SELF
>  ...
>  Programming Note [DevALV] and [DevCST]: When calculating watermark
>  values for 15/16bpp, assume 32bpp for purposes of calculation using
>  the high priority bandwidth analysis spreadsheet."

It does indeed.

> Let's do that.
> 
> Perhaps this might even help with the problem that resulted in
> commit 2ab1bc9df01d ("drm/i915: Disable self-refresh for untiled fbs on i915gm")
> 
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 1ac32428d4db..8cfef7683088 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -1604,6 +1604,9 @@ static void i9xx_update_wm(struct drm_crtc *unused_crtc)
>  		unsigned long line_time_us;
>  		int entries;
>  
> +		if (IS_I915GM(dev) || IS_I945GM(dev))
> +			cpp = 4;
> +

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre