Commit 759d4fff authored by Ville Syrjälä's avatar Ville Syrjälä
Browse files

drm/i915: Fix plane relative_data_rate calculation 



We are currently computing the relative data rates as
src_size * scale_factor where scale_factor is src_size / dst_size.
Thus relative data rate is src_size * src_size / dst_size,
which is just utter nonsense. What we really seem to want is
just a reasonable estimate on how much data will be fetched
which is just src_size. So let's do that instead.

Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220118092354.11631-4-ville.syrjala@linux.intel.com


Reviewed-by: default avatarStanislav Lisovskiy <stanislav.lisovskiy@intel.com>
parent 8a84e7a1

drivers/gpu/drm/i915/intel_pm.c

+2 −61
Original line number Diff line number Diff line
@@ -4356,55 +4356,6 @@ void skl_pipe_ddb_get_hw_state(struct intel_crtc *crtc, 
	intel_display_power_put(dev_priv, power_domain, wakeref);

}



/*

 * Determines the downscale amount of a plane for the purposes of watermark calculations.

 * The bspec defines downscale amount as:

 *

 * """

 * Horizontal down scale amount = maximum[1, Horizontal source size /

 *                                           Horizontal destination size]

 * Vertical down scale amount = maximum[1, Vertical source size /

 *                                         Vertical destination size]

 * Total down scale amount = Horizontal down scale amount *

 *                           Vertical down scale amount

 * """

 *

 * Return value is provided in 16.16 fixed point form to retain fractional part.

 * Caller should take care of dividing & rounding off the value.

 */

static uint_fixed_16_16_t

skl_plane_downscale_amount(const struct intel_crtc_state *crtc_state,

			   const struct intel_plane_state *plane_state)

{

	struct drm_i915_private *dev_priv = to_i915(crtc_state->uapi.crtc->dev);

	u32 src_w, src_h, dst_w, dst_h;

	uint_fixed_16_16_t fp_w_ratio, fp_h_ratio;

	uint_fixed_16_16_t downscale_h, downscale_w;



	if (drm_WARN_ON(&dev_priv->drm,

			!intel_wm_plane_visible(crtc_state, plane_state)))

		return u32_to_fixed16(0);



	/*

	 * Src coordinates are already rotated by 270 degrees for

	 * the 90/270 degree plane rotation cases (to match the

	 * GTT mapping), hence no need to account for rotation here.

	 *

	 * n.b., src is 16.16 fixed point, dst is whole integer.

	 */

	src_w = drm_rect_width(&plane_state->uapi.src) >> 16;

	src_h = drm_rect_height(&plane_state->uapi.src) >> 16;

	dst_w = drm_rect_width(&plane_state->uapi.dst);

	dst_h = drm_rect_height(&plane_state->uapi.dst);



	fp_w_ratio = div_fixed16(src_w, dst_w);

	fp_h_ratio = div_fixed16(src_h, dst_h);

	downscale_w = max_fixed16(fp_w_ratio, u32_to_fixed16(1));

	downscale_h = max_fixed16(fp_h_ratio, u32_to_fixed16(1));



	return mul_fixed16(downscale_w, downscale_h);

}



struct dbuf_slice_conf_entry {

	u8 active_pipes;

	u8 dbuf_mask[I915_MAX_PIPES];
@@ -4960,10 +4911,7 @@ skl_plane_relative_data_rate(const struct intel_crtc_state *crtc_state, 
{

	struct intel_plane *plane = to_intel_plane(plane_state->uapi.plane);

	const struct drm_framebuffer *fb = plane_state->hw.fb;

	u32 data_rate;

	u32 width = 0, height = 0;

	uint_fixed_16_16_t down_scale_amount;

	u64 rate;

	int width, height;



	if (!plane_state->uapi.visible)

		return 0;
@@ -4997,14 +4945,7 @@ skl_plane_relative_data_rate(const struct intel_crtc_state *crtc_state, 
		height /= 2;

	}



	data_rate = width * height;



	down_scale_amount = skl_plane_downscale_amount(crtc_state, plane_state);



	rate = mul_round_up_u32_fixed16(data_rate, down_scale_amount);



	rate *= fb->format->cpp[color_plane];

	return rate;

	return width * height * fb->format->cpp[color_plane];

}



static u64