Re: [PATCH 2/4] drm/i915/skl+: calculate ddb minimum allocation (v6)

[Matt Roper <matthew.d.roper@intel.com>]

On Wed, Jun 01, 2016 at 07:55:18PM +0530, Mahesh Kumar wrote:
> Reviewed-by: Kumar Mahesh <mahesh1.kumar@intel.com>

Merged to dinq; thanks for the review (and thanks for doing the initial
work this series was based on).


Matt

> 
> On Tuesday 31 May 2016 10:28 PM, Matt Roper wrote:
> >From: "Kumar, Mahesh" <mahesh1.kumar@intel.com>
> >
> >don't always use 8 ddb as minimum, instead calculate using proper
> >algorithm.
> >
> >v2: optimizations as per Matt's comments.
> >
> >v3 (by Matt):
> >  - Fix boolean logic for !fb test in skl_ddb_min_alloc()
> >  - Adjust negative tiling format comparisons in skl_ddb_min_alloc() to
> >    improve readability.
> >
> >v4 (by Matt):
> >  - Rebase onto recent atomic watermark changes
> >  - Slight tweaks to code flow to make the logic more closely match the
> >    description in the bspec.
> >
> >v5 (by Matt):
> >  - Handle minimum scanline calculation properly for 4 & 8 bpp formats.
> >    8bpp isn't actually possible right now, but it's listed in the bspec
> >    so I've included it here for forward compatibility (similar to how
> >    we have logic for NV12).
> >
> >v6 (by Matt):
> >  - Calculate plane_bpp correctly for non-NV12 formats. (Mahesh)
> >
> >Cc: matthew.d.roper@intel.com
> >Signed-off-by: Kumar, Mahesh <mahesh1.kumar@intel.com>
> >Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
> >---
> >  drivers/gpu/drm/i915/intel_pm.c | 70 ++++++++++++++++++++++++++++++++++++++---
> >  1 file changed, 65 insertions(+), 5 deletions(-)
> >
> >diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> >index 3cf36dc..4e0a952 100644
> >--- a/drivers/gpu/drm/i915/intel_pm.c
> >+++ b/drivers/gpu/drm/i915/intel_pm.c
> >@@ -3042,6 +3042,69 @@ skl_get_total_relative_data_rate(struct intel_crtc_state *intel_cstate)
> >  	return total_data_rate;
> >  }
> >+static uint16_t
> >+skl_ddb_min_alloc(const struct drm_plane_state *pstate,
> >+		  const int y)
> >+{
> >+	struct drm_framebuffer *fb = pstate->fb;
> >+	struct intel_plane_state *intel_pstate = to_intel_plane_state(pstate);
> >+	uint32_t src_w, src_h;
> >+	uint32_t min_scanlines = 8;
> >+	uint8_t plane_bpp;
> >+
> >+	if (WARN_ON(!fb))
> >+		return 0;
> >+
> >+	/* For packed formats, no y-plane, return 0 */
> >+	if (y && fb->pixel_format != DRM_FORMAT_NV12)
> >+		return 0;
> >+
> >+	/* For Non Y-tile return 8-blocks */
> >+	if (fb->modifier[0] != I915_FORMAT_MOD_Y_TILED &&
> >+	    fb->modifier[0] != I915_FORMAT_MOD_Yf_TILED)
> >+		return 8;
> >+
> >+	src_w = drm_rect_width(&intel_pstate->src) >> 16;
> >+	src_h = drm_rect_height(&intel_pstate->src) >> 16;
> >+
> >+	if (intel_rotation_90_or_270(pstate->rotation))
> >+		swap(src_w, src_h);
> >+
> >+	/* Halve UV plane width and height for NV12 */
> >+	if (fb->pixel_format == DRM_FORMAT_NV12 && !y) {
> >+		src_w /= 2;
> >+		src_h /= 2;
> >+	}
> >+
> >+	if (fb->pixel_format == DRM_FORMAT_NV12 && !y)
> >+		plane_bpp = drm_format_plane_cpp(fb->pixel_format, 1);
> >+	else
> >+		plane_bpp = drm_format_plane_cpp(fb->pixel_format, 0);
> >+
> >+	if (intel_rotation_90_or_270(pstate->rotation)) {
> >+		switch (plane_bpp) {
> >+		case 1:
> >+			min_scanlines = 32;
> >+			break;
> >+		case 2:
> >+			min_scanlines = 16;
> >+			break;
> >+		case 4:
> >+			min_scanlines = 8;
> >+			break;
> >+		case 8:
> >+			min_scanlines = 4;
> >+			break;
> >+		default:
> >+			WARN(1, "Unsupported pixel depth %u for rotation",
> >+			     plane_bpp);
> >+			min_scanlines = 32;
> >+		}
> >+	}
> >+
> >+	return DIV_ROUND_UP((4 * src_w * plane_bpp), 512) * min_scanlines/4 + 3;
> >+}
> >+
> >  static int
> >  skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
> >  		      struct skl_ddb_allocation *ddb /* out */)
> >@@ -3104,11 +3167,8 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
> >  			continue;
> >  		}
> >-		minimum[id] = 8;
> >-		if (pstate->fb->pixel_format == DRM_FORMAT_NV12)
> >-			y_minimum[id] = 8;
> >-		else
> >-			y_minimum[id] = 0;
> >+		minimum[id] = skl_ddb_min_alloc(pstate, 0);
> >+		y_minimum[id] = skl_ddb_min_alloc(pstate, 1);
> >  	}
> >  	for (i = 0; i < PLANE_CURSOR; i++) {
> 

-- 
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795
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