Re: [PATCH 5/8] drm/i915/gen9: minimum scanlines for Y tile is not always 4

[Lyude <cpaul@redhat.com>]

On Tue, 2016-09-06 at 21:52 -0300, Paulo Zanoni wrote:
> During watermarks calculations, this value is used in 3 different
> places. Only one of them was not using a hardcoded 4. Move the code
> up
> so everybody can benefit from the actual value.
> 
> This should only help on situations with Y tiling + 90/270 rotation +
> 1 or 2 bpp or NV12.
> 
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_pm.c | 56 +++++++++++++++++++++++------
> ------------
>  1 file changed, 32 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c
> b/drivers/gpu/drm/i915/intel_pm.c
> index f8ac928..5a23a91 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3499,7 +3499,8 @@ static uint32_t skl_wm_method1(uint32_t
> pixel_rate, uint8_t cpp, uint32_t latenc
>  
>  static uint32_t skl_wm_method2(uint32_t pixel_rate, uint32_t
> pipe_htotal,
>  			       uint32_t horiz_pixels, uint8_t cpp,
> -			       uint64_t tiling, uint32_t latency)
> +			       uint64_t tiling, uint32_t latency,
> +			       uint32_t y_min_scanlines)
>  {
>  	uint32_t ret;
>  	uint32_t plane_bytes_per_line, plane_blocks_per_line;
> @@ -3512,9 +3513,9 @@ static uint32_t skl_wm_method2(uint32_t
> pixel_rate, uint32_t pipe_htotal,
>  
>  	if (tiling == I915_FORMAT_MOD_Y_TILED ||
>  	    tiling == I915_FORMAT_MOD_Yf_TILED) {
> -		plane_bytes_per_line *= 4;
> +		plane_bytes_per_line *= y_min_scanlines;
>  		plane_blocks_per_line =
> DIV_ROUND_UP(plane_bytes_per_line, 512);
> -		plane_blocks_per_line /= 4;
> +		plane_blocks_per_line /= y_min_scanlines;
>  	} else if (tiling == DRM_FORMAT_MOD_NONE) {
>  		plane_blocks_per_line =
> DIV_ROUND_UP(plane_bytes_per_line, 512) + 1;
>  	} else {
> @@ -3571,6 +3572,7 @@ static int skl_compute_plane_wm(const struct
> drm_i915_private *dev_priv,
>  	uint8_t cpp;
>  	uint32_t width = 0, height = 0;
>  	uint32_t plane_pixel_rate;
> +	uint32_t y_min_scanlines;
>  
>  	if (latency == 0 || !cstate->base.active || !intel_pstate-
> >base.visible) {
>  		*enabled = false;
> @@ -3586,38 +3588,44 @@ static int skl_compute_plane_wm(const struct
> drm_i915_private *dev_priv,
>  	cpp = drm_format_plane_cpp(fb->pixel_format, 0);
>  	plane_pixel_rate = skl_adjusted_plane_pixel_rate(cstate,
> intel_pstate);
>  
> +	if (intel_rotation_90_or_270(pstate->rotation)) {
> +		int cpp = (fb->pixel_format == DRM_FORMAT_NV12) ?
> +			drm_format_plane_cpp(fb->pixel_format, 1) :
> +			drm_format_plane_cpp(fb->pixel_format, 0);
> +
> +		switch (cpp) {
> +		case 1:
> +			y_min_scanlines = 16;
> +			break;
> +		case 2:
> +			y_min_scanlines = 8;
> +			break;
> +		default:
> +			WARN(1, "Unsupported pixel depth for
> rotation");

This looks like it's leftover from the code that you moved around, but
we should be erroring out here and returning -EINVAL here so the
modeset actually fails.

> +		case 4:
> +			y_min_scanlines = 4;
> +			break;
> +		}
> +	} else {
> +		y_min_scanlines = 4;
> +	}
> +
>  	method1 = skl_wm_method1(plane_pixel_rate, cpp, latency);
>  	method2 = skl_wm_method2(plane_pixel_rate,
>  				 cstate-
> >base.adjusted_mode.crtc_htotal,
>  				 width,
>  				 cpp,
>  				 fb->modifier[0],
> -				 latency);
> +				 latency,
> +				 y_min_scanlines);
>  
>  	plane_bytes_per_line = width * cpp;
>  	plane_blocks_per_line = DIV_ROUND_UP(plane_bytes_per_line,
> 512);
>  
>  	if (fb->modifier[0] == I915_FORMAT_MOD_Y_TILED ||
>  	    fb->modifier[0] == I915_FORMAT_MOD_Yf_TILED) {
> -		uint32_t min_scanlines = 4;
> -		uint32_t y_tile_minimum;
> -		if (intel_rotation_90_or_270(pstate->rotation)) {
> -			int cpp = (fb->pixel_format ==
> DRM_FORMAT_NV12) ?
> -				drm_format_plane_cpp(fb-
> >pixel_format, 1) :
> -				drm_format_plane_cpp(fb-
> >pixel_format, 0);
> -
> -			switch (cpp) {
> -			case 1:
> -				min_scanlines = 16;
> -				break;
> -			case 2:
> -				min_scanlines = 8;
> -				break;
> -			case 8:
> -				WARN(1, "Unsupported pixel depth for
> rotation");
> -			}
> -		}
> -		y_tile_minimum = plane_blocks_per_line *
> min_scanlines;
> +		uint32_t y_tile_minimum = plane_blocks_per_line *
> +					  y_min_scanlines;
>  		selected_result = max(method2, y_tile_minimum);
>  	} else {
>  		if ((ddb_allocation / plane_blocks_per_line) >= 1)
> @@ -3632,7 +3640,7 @@ static int skl_compute_plane_wm(const struct
> drm_i915_private *dev_priv,
>  	if (level >= 1 && level <= 7) {
>  		if (fb->modifier[0] == I915_FORMAT_MOD_Y_TILED ||
>  		    fb->modifier[0] == I915_FORMAT_MOD_Yf_TILED)
> -			res_lines += 4;
> +			res_lines += y_min_scanlines;
>  		else
>  			res_blocks++;
>  	}
-- 
Cheers,
	Lyude
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