Re: [PATCH] drm/i915/skl: Correct other-pipe watermark update condition check

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Sep 21, 2015 at 11:32:44PM +0530, Kumar, Mahesh wrote:
> If ddb allocation for planes in current CRTC is changed, that doesn't
> lead to ddb allocation change for other CRTCs, because our DDB allocation
> is not dynamic according to plane parameters, ddb is allocated according
> to number of CRTC enabled, & divided equally among CTRC's.
> 
> In current condition check during Watermark calculation, if number of
> plane/ddb allocation changes for current CRTC, Watermark for other pipes
> are recalculated. But there is no change in DDB allocation of other pipe
> so watermark is also not changed, This leads to warning messages.
> WARN_ON(!wm_changed)
> 
> This patch corrects this and check if DDB allocation for pipes is changed,
> then only recalculate watermarks.
> 
> Signed-off-by: Kumar, Mahesh <mahesh1.kumar@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 12 +++++-------
>  1 file changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 62de97e..a1ed920 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3127,14 +3127,12 @@ static bool skl_ddb_allocation_changed(const struct skl_ddb_allocation *new_ddb,
>  	struct drm_device *dev = intel_crtc->base.dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	const struct skl_ddb_allocation *cur_ddb = &dev_priv->wm.skl_hw.ddb;
> -	enum pipe pipe = intel_crtc->pipe;
> -
> -	if (memcmp(new_ddb->plane[pipe], cur_ddb->plane[pipe],
> -		   sizeof(new_ddb->plane[pipe])))
> -		return true;
>  
> -	if (memcmp(&new_ddb->cursor[pipe], &cur_ddb->cursor[pipe],
> -		    sizeof(new_ddb->cursor[pipe])))
> +	/*
> +	 * If ddb allocation of pipes chenged, it may require recalculation of
> +	 * watermarks
> +	 */
> +	if (memcmp(new_ddb->pipe, cur_ddb->pipe, sizeof(new_ddb->pipe)))
>  		return true;

I still have the cursor code here, this patch needs to be rebased.
-Daniel

>  
>  	return false;
> -- 
> 1.9.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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