drm/i915/display: Compute vrr_vsync params

Compute vrr_vsync_start/end, which sets the position
for hardware to send the Vsync at a fixed position
relative to the end of the Vblank.

--v2:
- Updated VSYNC_START/END macros to VRR_VSYNC_START/END. (Ankit)
- Updated bit fields of VRR_VSYNC_START/END. (Ankit)

--v3:
- Add PIPE_CONF_CHECK_I(vrr.vsync_start/end).
- Read/write vrr_vsync params only when we intend to send
adaptive_sync sdp.

--v4:
- Use VRR_SYNC_START/END macros correctly.

--v5:
- Send AS SDP only when VRR is enabled.

--v6:
- Add TRANS_VRR_VSYNC before enabling VRR as per bspec. (Ankit)
Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240322031157.3823909-9-mitulkumar.ajitkumar.golani@intel.com

drivers/gpu/drm/i915/display/intel_display.c

@@ -5385,6 +5385,8 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
 		PIPE_CONF_CHECK_I(vrr.flipline);
 		PIPE_CONF_CHECK_I(vrr.pipeline_full);
 		PIPE_CONF_CHECK_I(vrr.guardband);
+		PIPE_CONF_CHECK_I(vrr.vsync_start);
+		PIPE_CONF_CHECK_I(vrr.vsync_end);
 	}
 
 #undef PIPE_CONF_CHECK_X

drivers/gpu/drm/i915/display/intel_display_types.h

@@ -1434,6 +1434,7 @@ struct intel_crtc_state {
 		bool enable, in_range;
 		u8 pipeline_full;
 		u16 flipline, vmin, vmax, guardband;
+		u32 vsync_end, vsync_start;
 	} vrr;
 
 	/* Stream Splitter for eDP MSO */

drivers/gpu/drm/i915/display/intel_vrr.c

@@ -9,6 +9,7 @@
 #include "intel_de.h"
 #include "intel_display_types.h"
 #include "intel_vrr.h"
+#include "intel_dp.h"
 
 bool intel_vrr_is_capable(struct intel_connector *connector)
 {
@@ -113,6 +114,7 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
 	struct drm_i915_private *i915 = to_i915(crtc->base.dev);
 	struct intel_connector *connector =
 		to_intel_connector(conn_state->connector);
+	struct intel_dp *intel_dp = intel_attached_dp(connector);
 	struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
 	const struct drm_display_info *info = &connector->base.display_info;
 	int vmin, vmax;
@@ -165,6 +167,14 @@ intel_vrr_compute_config(struct intel_crtc_state *crtc_state,
 	if (crtc_state->uapi.vrr_enabled) {
 		crtc_state->vrr.enable = true;
 		crtc_state->mode_flags |= I915_MODE_FLAG_VRR;
+		if (intel_dp_as_sdp_supported(intel_dp)) {
+			crtc_state->vrr.vsync_start =
+				(crtc_state->hw.adjusted_mode.crtc_vtotal -
+					crtc_state->hw.adjusted_mode.vsync_start);
+			crtc_state->vrr.vsync_end =
+				(crtc_state->hw.adjusted_mode.crtc_vtotal -
+					crtc_state->hw.adjusted_mode.vsync_end);
+		}
 	}
 }
 
@@ -240,6 +250,12 @@ void intel_vrr_enable(const struct intel_crtc_state *crtc_state)
 		return;
 
 	intel_de_write(dev_priv, TRANS_PUSH(cpu_transcoder), TRANS_PUSH_EN);
+
+	if (HAS_AS_SDP(dev_priv))
+		intel_de_write(dev_priv, TRANS_VRR_VSYNC(cpu_transcoder),
+			       VRR_VSYNC_END(crtc_state->vrr.vsync_end) |
+			       VRR_VSYNC_START(crtc_state->vrr.vsync_start));
+
 	intel_de_write(dev_priv, TRANS_VRR_CTL(cpu_transcoder),
 		       VRR_CTL_VRR_ENABLE | trans_vrr_ctl(crtc_state));
 }
@@ -258,13 +274,16 @@ void intel_vrr_disable(const struct intel_crtc_state *old_crtc_state)
 	intel_de_wait_for_clear(dev_priv, TRANS_VRR_STATUS(cpu_transcoder),
 				VRR_STATUS_VRR_EN_LIVE, 1000);
 	intel_de_write(dev_priv, TRANS_PUSH(cpu_transcoder), 0);
+
+	if (HAS_AS_SDP(dev_priv))
+		intel_de_write(dev_priv, TRANS_VRR_VSYNC(cpu_transcoder), 0);
 }
 
 void intel_vrr_get_config(struct intel_crtc_state *crtc_state)
 {
 	struct drm_i915_private *dev_priv = to_i915(crtc_state->uapi.crtc->dev);
 	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
-	u32 trans_vrr_ctl;
+	u32 trans_vrr_ctl, trans_vrr_vsync;
 
 	trans_vrr_ctl = intel_de_read(dev_priv, TRANS_VRR_CTL(cpu_transcoder));
 
@@ -284,6 +303,16 @@ void intel_vrr_get_config(struct intel_crtc_state *crtc_state)
 		crtc_state->vrr.vmin = intel_de_read(dev_priv, TRANS_VRR_VMIN(cpu_transcoder)) + 1;
 	}
 
-	if (crtc_state->vrr.enable)
+	if (crtc_state->vrr.enable) {
 		crtc_state->mode_flags |= I915_MODE_FLAG_VRR;
+
+		if (HAS_AS_SDP(dev_priv)) {
+			trans_vrr_vsync =
+				intel_de_read(dev_priv, TRANS_VRR_VSYNC(cpu_transcoder));
+			crtc_state->vrr.vsync_start =
+				REG_FIELD_GET(VRR_VSYNC_START_MASK, trans_vrr_vsync);
+			crtc_state->vrr.vsync_end =
+				REG_FIELD_GET(VRR_VSYNC_END_MASK, trans_vrr_vsync);
+		}
+	}
 }

drivers/gpu/drm/i915/i915_reg.h

@@ -2093,6 +2093,13 @@
 #define   TRANS_PUSH_EN			REG_BIT(31)
 #define   TRANS_PUSH_SEND		REG_BIT(30)
 
+#define _TRANS_VRR_VSYNC_A		0x60078
+#define TRANS_VRR_VSYNC(trans)		_MMIO_TRANS2(trans, _TRANS_VRR_VSYNC_A)
+#define VRR_VSYNC_END_MASK		REG_GENMASK(28, 16)
+#define VRR_VSYNC_END(vsync_end)	REG_FIELD_PREP(VRR_VSYNC_END_MASK, (vsync_end))
+#define VRR_VSYNC_START_MASK		REG_GENMASK(12, 0)
+#define VRR_VSYNC_START(vsync_start)	REG_FIELD_PREP(VRR_VSYNC_START_MASK, (vsync_start))
+
 /* VGA port control */
 #define ADPA			_MMIO(0x61100)
 #define PCH_ADPA                _MMIO(0xe1100)