[Intel-gfx] [RFC 3/3] drm/i915: Compute CMRR and calculate vtotal

[Mitul Golani]

Compute Fixed Average Vtotal/CMRR with resepect to
userspace VRR enablement. Also calculate required
parameters in case of CMRR is  enabled. During
intel_vrr_compute_config, CMRR is getting enabled
based on userspace has enabled Adaptive Sync Vtotal
mode (Legacy VRR) or not.

Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani at intel.com>
---
 drivers/gpu/drm/i915/display/intel_display.c  |  1 +
 .../drm/i915/display/intel_display_device.h   |  1 +
 drivers/gpu/drm/i915/display/intel_vrr.c      | 81 +++++++++++++++++--
 3 files changed, 78 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index f5a69309e65a..d61790f8ebb4 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -5479,6 +5479,7 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
 		PIPE_CONF_CHECK_I(vrr.guardband);
 		PIPE_CONF_CHECK_LLI(cmrr.cmrr_m);
 		PIPE_CONF_CHECK_LLI(cmrr.cmrr_n);
+		PIPE_CONF_CHECK_BOOL(cmrr.enable);
 	}
 
 #undef PIPE_CONF_CHECK_X
diff --git a/drivers/gpu/drm/i915/display/intel_display_device.h b/drivers/gpu/drm/i915/display/intel_display_device.h
index 4299cc452e05..66cbc3a6bbe8 100644
--- a/drivers/gpu/drm/i915/display/intel_display_device.h
+++ b/drivers/gpu/drm/i915/display/intel_display_device.h
@@ -68,6 +68,7 @@ struct drm_printer;
 #define HAS_TRANSCODER(i915, trans)	((DISPLAY_RUNTIME_INFO(i915)->cpu_transcoder_mask & \
 					  BIT(trans)) != 0)
 #define HAS_VRR(i915)			(DISPLAY_VER(i915) >= 11)
+#define HAS_CMRR(i915)			(DISPLAY_VER(i915) >= 20)
 #define INTEL_NUM_PIPES(i915)		(hweight8(DISPLAY_RUNTIME_INFO(i915)->pipe_mask))
 #define I915_HAS_HOTPLUG(i915)		(DISPLAY_INFO(i915)->has_hotplug)
 #define OVERLAY_NEEDS_PHYSICAL(i915)	(DISPLAY_INFO(i915)->overlay_needs_physical)
diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
index 1e33661062b3..4a056a71b68d 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -105,6 +105,52 @@ int intel_vrr_vmax_vblank_start(const struct intel_crtc_state *crtc_state)
 	return crtc_state->vrr.vmax - intel_vrr_vblank_exit_length(crtc_state);
 }
 
+static int
+is_cmrr_frac_required(struct intel_crtc_state *crtc_state)
+{
+	int target_refresh_k, actual_refresh_k;
+	struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
+
+	target_refresh_k = drm_mode_vrefresh(adjusted_mode) * 1000;
+	actual_refresh_k = DIV_ROUND_UP(adjusted_mode->crtc_clock * 1000,
+					adjusted_mode->crtc_htotal) * 1000;
+	actual_refresh_k /= adjusted_mode->crtc_vtotal;
+
+	if (actual_refresh_k == target_refresh_k)
+		return false;
+
+	return true;
+}
+
+static unsigned int
+cmrr_get_vtotal(struct intel_crtc_state *crtc_state)
+{
+	unsigned int muliplierM = 1, muliplierN = 1, vtotal;
+	unsigned int actual_refresh_rate, desired_refresh_rate;
+	unsigned long long actual_pixel_rate;
+	struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
+
+	actual_refresh_rate = DIV_ROUND_UP(adjusted_mode->crtc_clock * 1000,
+					   adjusted_mode->crtc_htotal) * 1000;
+	actual_refresh_rate /= adjusted_mode->crtc_vtotal;
+	desired_refresh_rate = drm_mode_vrefresh(adjusted_mode);
+	actual_pixel_rate = actual_refresh_rate * adjusted_mode->crtc_vtotal;
+	actual_pixel_rate = (actual_pixel_rate * adjusted_mode->crtc_htotal) / 1000;
+
+	if (is_cmrr_frac_required(crtc_state)) {
+		muliplierM = 1001;
+		muliplierN = 1000;
+	}
+
+	crtc_state->cmrr.cmrr_n = DIV_ROUND_UP(desired_refresh_rate *
+			adjusted_mode->crtc_htotal * muliplierN, muliplierM) * muliplierN;
+	vtotal = DIV_ROUND_UP(actual_pixel_rate * muliplierN, crtc_state->cmrr.cmrr_n);
+	crtc_state->cmrr.cmrr_m =
+		(actual_pixel_rate * muliplierM) % crtc_state->cmrr.cmrr_n;
+
+	return vtotal;
+}
+
 void
 intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
 			 struct drm_connector_state *conn_state)
@@ -149,6 +195,27 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
 
 	crtc_state->vrr.flipline = crtc_state->vrr.vmin + 1;
 
+	/*
+	 * When panel is VRR capable and userspace has
+	 * not enabled adaptive sync mode then Fixed Average
+	 * Vtotal mode should be enabled.
+	 */
+	if (crtc_state->uapi.vrr_enabled) {
+		crtc_state->vrr.enable = true;
+		if (HAS_CMRR(i915))
+			crtc_state->cmrr.enable = false;
+		crtc_state->mode_flags |= I915_MODE_FLAG_VRR;
+	} else {
+		crtc_state->vrr.enable = false;
+		if (HAS_CMRR(i915)) {
+			crtc_state->cmrr.enable = true;
+			crtc_state->vrr.vmax = cmrr_get_vtotal(crtc_state);
+			crtc_state->vrr.vmin = crtc_state->vrr.vmax;
+			crtc_state->vrr.flipline = crtc_state->vrr.vmin;
+			crtc_state->mode_flags |= I915_MODE_FLAG_VRR;
+		}
+	}
+
 	/*
 	 * For XE_LPD+, we use guardband and pipeline override
 	 * is deprecated.
@@ -161,11 +228,6 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
 			min(255, crtc_state->vrr.vmin - adjusted_mode->crtc_vblank_start -
 			    crtc_state->framestart_delay - 1);
 	}
-
-	if (crtc_state->uapi.vrr_enabled) {
-		crtc_state->vrr.enable = true;
-		crtc_state->mode_flags |= I915_MODE_FLAG_VRR;
-	}
 }
 
 static u32 trans_vrr_ctl(const struct intel_crtc_state *crtc_state)
@@ -295,6 +357,15 @@ void intel_vrr_get_config(struct intel_crtc_state *crtc_state)
 
 	trans_vrr_ctl = intel_de_read(dev_priv, TRANS_VRR_CTL(cpu_transcoder));
 
+	if (HAS_CMRR(dev_priv)) {
+		crtc_state->cmrr.enable = (trans_vrr_ctl & VRR_CTL_CMRR_ENABLE) &&
+					  (trans_vrr_ctl & VRR_CTL_VRR_ENABLE);
+		crtc_state->vrr.enable = trans_vrr_ctl & VRR_CTL_VRR_ENABLE &&
+					 !(trans_vrr_ctl & VRR_CTL_CMRR_ENABLE);
+	} else {
+		crtc_state->vrr.enable = trans_vrr_ctl & VRR_CTL_VRR_ENABLE;
+	}
+
 	if (crtc_state->cmrr.enable) {
 		cmrr_n_hi = intel_de_read(dev_priv, TRANS_CMRR_N_HI(cpu_transcoder));
 		cmrr_n_lo = intel_de_read(dev_priv, TRANS_CMRR_N_LO(cpu_transcoder));
-- 
2.25.1