Re: [PATCH] drm/i915/skl: Use proper plane dimensions for DDB and WM calculations

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

On Mon, Dec 21, 2015 at 07:31:17AM -0800, Matt Roper wrote:
> In commit
> 
>         commit 024c9045221fe45482863c47c4b4c47d37f97cbf
>         Author: Matt Roper <matthew.d.roper@intel.com>
>         Date:   Thu Sep 24 15:53:11 2015 -0700
> 
>             drm/i915/skl: Eliminate usage of pipe_wm_parameters from SKL-style WM (v4)
> 
> I fumbled while converting the dimensions stored in the plane_parameters
> structure to the values stored in plane state and accidentally replaced
> the plane dimensions with the pipe dimensions in both the DDB allocation
> function and the WM calculation function.  On the DDB side this is
> harmless since we effectively treat all of our non-cursor planes as
> full-screen which may not be optimal, but generally won't cause any
> problems either (and in 99% of the cases where there's no sprite plane
> usage or primary plane windowing, there's no effect at all).  On the WM
> calculation side there's more potential for this fumble to cause actual
> problems since cursors also get miscalculated.
> 
> Cc: Ville Syrjälä <ville.syrjala@intel.com>
> Cc: "Kondapally, Kalyan" <kalyan.kondapally@intel.com>
> Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 24 +++++++++++++-----------
>  1 file changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 8d0d6f5..f4d4cc7 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -2845,25 +2845,22 @@ skl_plane_relative_data_rate(const struct intel_crtc_state *cstate,
>  			     const struct drm_plane_state *pstate,
>  			     int y)
>  {
> -	struct intel_crtc *intel_crtc = to_intel_crtc(cstate->base.crtc);
> +	struct intel_plane_state *intel_pstate = to_intel_plane_state(pstate);
>  	struct drm_framebuffer *fb = pstate->fb;
> +	unsigned w = drm_rect_width(&intel_pstate->dst);
> +	unsigned h = drm_rect_height(&intel_pstate->dst);

I think you're supposed to use the src dimensions in most places.

>  
>  	/* for planar format */
>  	if (fb->pixel_format == DRM_FORMAT_NV12) {
>  		if (y)  /* y-plane data rate */
> -			return intel_crtc->config->pipe_src_w *
> -				intel_crtc->config->pipe_src_h *
> -				drm_format_plane_cpp(fb->pixel_format, 0);
> +			return w * h * drm_format_plane_cpp(fb->pixel_format, 0);
>  		else    /* uv-plane data rate */
> -			return (intel_crtc->config->pipe_src_w/2) *
> -				(intel_crtc->config->pipe_src_h/2) *
> +			return (w/2) * (h/2) *
>  				drm_format_plane_cpp(fb->pixel_format, 1);
>  	}
>  
>  	/* for packed formats */
> -	return intel_crtc->config->pipe_src_w *
> -		intel_crtc->config->pipe_src_h *
> -		drm_format_plane_cpp(fb->pixel_format, 0);
> +	return w * h * drm_format_plane_cpp(fb->pixel_format, 0);
>  }
>  
>  /*
> @@ -2960,6 +2957,8 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
>  	 * FIXME: we may not allocate every single block here.
>  	 */
>  	total_data_rate = skl_get_total_relative_data_rate(cstate);
> +	if (!total_data_rate)
> +		return;
>  
>  	start = alloc->start;
>  	for_each_intel_plane_on_crtc(dev, intel_crtc, intel_plane) {
> @@ -3093,12 +3092,15 @@ static bool skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
>  {
>  	struct drm_plane *plane = &intel_plane->base;
>  	struct drm_framebuffer *fb = plane->state->fb;
> +	struct intel_plane_state *intel_pstate =
> +		to_intel_plane_state(plane->state);
>  	uint32_t latency = dev_priv->wm.skl_latency[level];
>  	uint32_t method1, method2;
>  	uint32_t plane_bytes_per_line, plane_blocks_per_line;
>  	uint32_t res_blocks, res_lines;
>  	uint32_t selected_result;
>  	uint8_t bytes_per_pixel;
> +	unsigned w = drm_rect_width(&intel_pstate->dst);
>  
>  	if (latency == 0 || !cstate->base.active || !fb)
>  		return false;
> @@ -3109,12 +3111,12 @@ static bool skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
>  				 latency);
>  	method2 = skl_wm_method2(skl_pipe_pixel_rate(cstate),
>  				 cstate->base.adjusted_mode.crtc_htotal,
> -				 cstate->pipe_src_w,
> +				 w,
>  				 bytes_per_pixel,
>  				 fb->modifier[0],
>  				 latency);
>  
> -	plane_bytes_per_line = cstate->pipe_src_w * bytes_per_pixel;
> +	plane_bytes_per_line = w * bytes_per_pixel;
>  	plane_blocks_per_line = DIV_ROUND_UP(plane_bytes_per_line, 512);
>  
>  	if (fb->modifier[0] == I915_FORMAT_MOD_Y_TILED ||
> -- 
> 2.1.4
> 
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-- 
Ville Syrjälä
Intel OTC
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