drm/i915/vrr: Prepare for fixed refresh rate timings

Currently we always compute the timings as if vrr is enabled.
With this approach the state checker becomes complicated when we
introduce fixed refresh rate mode with vrr timing generator.

To avoid the complications, instead of always computing vrr timings, we
compute vrr timings based on uapi.vrr_enable knob.
So when the knob is disabled we always compute vmin=flipline=vmax.

v2: Use actual timings without any adjustments while preparing for
fixed timings in compute_config. (Ville)
v3: Avoid setting fixed timings if !vrr_possible().
v4: Move vmin adjustement after all other timings are complete. (Ville)

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> (#v2)
Link: https://patchwork.freedesktop.org/patch/msgid/20250311093751.1329043-8-ankit.k.nautiyal@intel.com

1 files changed, 82 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
index e0573e28014b..622a70e21737 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -246,6 +246,72 @@ void intel_vrr_compute_vrr_timings(struct intel_crtc_state *crtc_state)
 	crtc_state->mode_flags |= I915_MODE_FLAG_VRR;
 }
 
+/*
+ * For fixed refresh rate mode Vmin, Vmax and Flipline all are set to
+ * Vtotal value.
+ */
+static
+int intel_vrr_fixed_rr_vtotal(const struct intel_crtc_state *crtc_state)
+{
+	struct intel_display *display = to_intel_display(crtc_state);
+	int crtc_vtotal = crtc_state->hw.adjusted_mode.crtc_vtotal;
+
+	if (DISPLAY_VER(display) >= 13)
+		return crtc_vtotal;
+	else
+		return crtc_vtotal -
+			intel_vrr_real_vblank_delay(crtc_state);
+}
+
+static
+int intel_vrr_fixed_rr_vmax(const struct intel_crtc_state *crtc_state)
+{
+	return intel_vrr_fixed_rr_vtotal(crtc_state);
+}
+
+static
+int intel_vrr_fixed_rr_vmin(const struct intel_crtc_state *crtc_state)
+{
+	struct intel_display *display = to_intel_display(crtc_state);
+
+	return intel_vrr_fixed_rr_vtotal(crtc_state) -
+		intel_vrr_flipline_offset(display);
+}
+
+static
+int intel_vrr_fixed_rr_flipline(const struct intel_crtc_state *crtc_state)
+{
+	return intel_vrr_fixed_rr_vtotal(crtc_state);
+}
+
+static
+void intel_vrr_set_fixed_rr_timings(const struct intel_crtc_state *crtc_state)
+{
+	struct intel_display *display = to_intel_display(crtc_state);
+	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
+
+	if (!intel_vrr_possible(crtc_state))
+		return;
+
+	intel_de_write(display, TRANS_VRR_VMIN(display, cpu_transcoder),
+		       intel_vrr_fixed_rr_vmin(crtc_state) - 1);
+	intel_de_write(display, TRANS_VRR_VMAX(display, cpu_transcoder),
+		       intel_vrr_fixed_rr_vmax(crtc_state) - 1);
+	intel_de_write(display, TRANS_VRR_FLIPLINE(display, cpu_transcoder),
+		       intel_vrr_fixed_rr_flipline(crtc_state) - 1);
+}
+
+static
+void intel_vrr_compute_fixed_rr_timings(struct intel_crtc_state *crtc_state)
+{
+	/*
+	 * For fixed rr,  vmin = vmax = flipline.
+	 * vmin is already set to crtc_vtotal set vmax and flipline the same.
+	 */
+	crtc_state->vrr.vmax = crtc_state->hw.adjusted_mode.crtc_vtotal;
+	crtc_state->vrr.flipline = crtc_state->hw.adjusted_mode.crtc_vtotal;
+}
+
 static
 int intel_vrr_compute_vmin(struct intel_crtc_state *crtc_state)
 {
@@ -314,6 +380,13 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
 
 	crtc_state->vrr.flipline = crtc_state->vrr.vmin;
 
+	if (crtc_state->uapi.vrr_enabled)
+		intel_vrr_compute_vrr_timings(crtc_state);
+	else if (is_cmrr_frac_required(crtc_state) && is_edp)
+		intel_vrr_compute_cmrr_timings(crtc_state);
+	else
+		intel_vrr_compute_fixed_rr_timings(crtc_state);
+
 	/*
 	 * flipline determines the min vblank length the hardware will
 	 * generate, and on ICL/TGL flipline>=vmin+1, hence we reduce
@@ -321,11 +394,6 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
 	 */
 	crtc_state->vrr.vmin -= intel_vrr_flipline_offset(display);
 
-	if (crtc_state->uapi.vrr_enabled)
-		intel_vrr_compute_vrr_timings(crtc_state);
-	else if (is_cmrr_frac_required(crtc_state) && is_edp)
-		intel_vrr_compute_cmrr_timings(crtc_state);
-
 	if (HAS_AS_SDP(display)) {
 		crtc_state->vrr.vsync_start =
 			(crtc_state->hw.adjusted_mode.crtc_vtotal -
@@ -496,6 +564,13 @@ void intel_vrr_enable(const struct intel_crtc_state *crtc_state)
 	if (!crtc_state->vrr.enable)
 		return;
 
+	intel_de_write(display, TRANS_VRR_VMIN(display, cpu_transcoder),
+		       crtc_state->vrr.vmin - 1);
+	intel_de_write(display, TRANS_VRR_VMAX(display, cpu_transcoder),
+		       crtc_state->vrr.vmax - 1);
+	intel_de_write(display, TRANS_VRR_FLIPLINE(display, cpu_transcoder),
+		       crtc_state->vrr.flipline - 1);
+
 	intel_de_write(display, TRANS_PUSH(display, cpu_transcoder),
 		       TRANS_PUSH_EN);
 
@@ -523,6 +598,8 @@ void intel_vrr_disable(const struct intel_crtc_state *old_crtc_state)
 				TRANS_VRR_STATUS(display, cpu_transcoder),
 				VRR_STATUS_VRR_EN_LIVE, 1000);
 	intel_de_write(display, TRANS_PUSH(display, cpu_transcoder), 0);
+
+	intel_vrr_set_fixed_rr_timings(old_crtc_state);
 }
 
 static