[PATCH v2 7/9] drm/i915/wm: Add WM0 prefill helpers

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

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Add skl_wm0_prefill_lines() (based on the actual state) and
skl_wm0_prefill_lines_worst() (worst case estimate) which
tell us how many extra lines are needed in prefill for WM0.

The returned numbers are in .16 binary fixed point.

TODO: skl_wm0_prefill_lines_worst() is a bit rough still

v2: Drop all pre-icl FIXMEs since this only gets used for VRR guardband

Reviewed-by: Uma Shankar <uma.shankar@intel.com> #v1
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/i915/display/skl_scaler.c    | 32 ++++++++++-
 drivers/gpu/drm/i915/display/skl_scaler.h    |  4 ++
 drivers/gpu/drm/i915/display/skl_watermark.c | 57 ++++++++++++++++++++
 drivers/gpu/drm/i915/display/skl_watermark.h |  3 ++
 4 files changed, 95 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/skl_scaler.c b/drivers/gpu/drm/i915/display/skl_scaler.c
index 47cdea75d27c..65f2eb528161 100644
--- a/drivers/gpu/drm/i915/display/skl_scaler.c
+++ b/drivers/gpu/drm/i915/display/skl_scaler.c
@@ -1083,7 +1083,37 @@ static unsigned int _skl_scaler_max_scale(const struct intel_crtc_state *crtc_st
 					       crtc_state->hw.pipe_mode.crtc_clock));
 }
 
-static unsigned int skl_scaler_max_scale(const struct intel_crtc_state *crtc_state)
+unsigned int skl_scaler_max_total_scale(const struct intel_crtc_state *crtc_state)
+{
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
+	unsigned int max_scale;
+
+	if (crtc->num_scalers < 1)
+		return 0x10000;
+
+	/* FIXME find out the max downscale factors properly */
+	max_scale = 9 << 16;
+	if (crtc->num_scalers > 1)
+		max_scale *= 9;
+
+	return _skl_scaler_max_scale(crtc_state, max_scale);
+}
+
+unsigned int skl_scaler_max_hscale(const struct intel_crtc_state *crtc_state)
+{
+	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
+	unsigned int max_scale;
+
+	if (crtc->num_scalers < 1)
+		return 0x10000;
+
+	/* FIXME find out the max downscale factors properly */
+	max_scale = 3 << 16;
+
+	return _skl_scaler_max_scale(crtc_state, max_scale);
+}
+
+unsigned int skl_scaler_max_scale(const struct intel_crtc_state *crtc_state)
 {
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
 	unsigned int max_scale;
diff --git a/drivers/gpu/drm/i915/display/skl_scaler.h b/drivers/gpu/drm/i915/display/skl_scaler.h
index 6fab40d2b4ee..5deabca909e6 100644
--- a/drivers/gpu/drm/i915/display/skl_scaler.h
+++ b/drivers/gpu/drm/i915/display/skl_scaler.h
@@ -46,6 +46,10 @@ void adl_scaler_ecc_mask(const struct intel_crtc_state *crtc_state);
 
 void adl_scaler_ecc_unmask(const struct intel_crtc_state *crtc_state);
 
+unsigned int skl_scaler_max_total_scale(const struct intel_crtc_state *crtc_state);
+unsigned int skl_scaler_max_scale(const struct intel_crtc_state *crtc_state);
+unsigned int skl_scaler_max_hscale(const struct intel_crtc_state *crtc_state);
+
 unsigned int skl_scaler_1st_prefill_adjustment_worst(const struct intel_crtc_state *crtc_state);
 unsigned int skl_scaler_2nd_prefill_adjustment_worst(const struct intel_crtc_state *crtc_state);
 unsigned int skl_scaler_1st_prefill_lines_worst(const struct intel_crtc_state *crtc_state);
diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
index 06e5e6c77d2e..700707a91c70 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -30,6 +30,7 @@
 #include "intel_plane.h"
 #include "intel_vblank.h"
 #include "intel_wm.h"
+#include "skl_scaler.h"
 #include "skl_universal_plane_regs.h"
 #include "skl_watermark.h"
 #include "skl_watermark_regs.h"
@@ -2245,6 +2246,57 @@ skl_is_vblank_too_short(const struct intel_crtc_state *crtc_state,
 		intel_crtc_vblank_length(crtc_state);
 }
 
+unsigned int skl_wm0_prefill_lines_worst(const struct intel_crtc_state *crtc_state)
+{
+	struct intel_display *display = to_intel_display(crtc_state);
+	struct intel_plane *plane = to_intel_plane(crtc_state->uapi.crtc->primary);
+	const struct drm_display_mode *pipe_mode = &crtc_state->hw.pipe_mode;
+	int ret, pixel_rate, width, level = 0;
+	const struct drm_format_info *info;
+	struct skl_wm_level wm = {};
+	struct skl_wm_params wp;
+	unsigned int latency;
+	u64 modifier;
+	u32 format;
+
+	/* only expected to be used for VRR guardband calculation */
+	drm_WARN_ON(display->drm, !HAS_VRR(display));
+
+	/* FIXME rather ugly to pick this by hand but maybe no better way? */
+	format = DRM_FORMAT_XBGR16161616F;
+	if (HAS_4TILE(display))
+		modifier = I915_FORMAT_MOD_4_TILED;
+	else
+		modifier = I915_FORMAT_MOD_Y_TILED;
+
+	info = drm_get_format_info(display->drm, format, modifier);
+
+	pixel_rate = DIV_ROUND_UP_ULL(mul_u32_u32(skl_scaler_max_total_scale(crtc_state),
+						  pipe_mode->crtc_clock),
+				      0x10000);
+
+	/* FIXME limit to max plane width? */
+	width = DIV_ROUND_UP_ULL(mul_u32_u32(skl_scaler_max_hscale(crtc_state),
+					     pipe_mode->crtc_hdisplay),
+				 0x10000);
+
+	/* FIXME is 90/270 rotation worse than 0/180? */
+	ret = skl_compute_wm_params(crtc_state, width, info,
+				    modifier, DRM_MODE_ROTATE_0,
+				    pixel_rate, &wp, 0, 1);
+	drm_WARN_ON(display->drm, ret);
+
+	latency = skl_wm_latency(display, level, &wp);
+
+	skl_compute_plane_wm(crtc_state, plane, level, latency, &wp, &wm, &wm);
+
+	/* FIXME is this sane? */
+	if (wm.min_ddb_alloc == U16_MAX)
+		wm.lines = skl_wm_max_lines(display);
+
+	return wm.lines << 16;
+}
+
 static int skl_max_wm0_lines(const struct intel_crtc_state *crtc_state)
 {
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
@@ -2261,6 +2313,11 @@ static int skl_max_wm0_lines(const struct intel_crtc_state *crtc_state)
 	return wm0_lines;
 }
 
+unsigned int skl_wm0_prefill_lines(const struct intel_crtc_state *crtc_state)
+{
+	return skl_max_wm0_lines(crtc_state) << 16;
+}
+
 /*
  * TODO: In case we use PKG_C_LATENCY to allow C-states when the delayed vblank
  * size is too small for the package C exit latency we need to notify PSR about
diff --git a/drivers/gpu/drm/i915/display/skl_watermark.h b/drivers/gpu/drm/i915/display/skl_watermark.h
index 62790816f030..6bc2ec9164bf 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.h
+++ b/drivers/gpu/drm/i915/display/skl_watermark.h
@@ -79,5 +79,8 @@ void intel_program_dpkgc_latency(struct intel_atomic_state *state);
 
 bool intel_dbuf_pmdemand_needs_update(struct intel_atomic_state *state);
 
+unsigned int skl_wm0_prefill_lines_worst(const struct intel_crtc_state *crtc_state);
+unsigned int skl_wm0_prefill_lines(const struct intel_crtc_state *crtc_state);
+
 #endif /* __SKL_WATERMARK_H__ */
 
-- 
2.49.1