drm/amd/display: Skip modeset for front porch change

[Why]
A seamless transition between modes can be performed if the new incoming
mode has the same timing parameters as the optimized mode on a display with a
variable vtotal min/max.

Smooth video playback usecases can be enabled with this seamless transition by
switching to a new mode which has a refresh rate matching the video.

[How]
Skip full modeset if userspace requested a compatible freesync mode which only
differs in the front porch timing from the current mode.
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -213,6 +213,9 @@ static bool amdgpu_dm_psr_disable_all(struct amdgpu_display_manager *dm);
 static const struct drm_format_info *
 amd_get_format_info(const struct drm_mode_fb_cmd2 *cmd);
 
+static bool
+is_timing_unchanged_for_freesync(struct drm_crtc_state *old_crtc_state,
+				 struct drm_crtc_state *new_crtc_state);
 /*
  * dm_vblank_get_counter
  *
@@ -336,6 +339,17 @@ static inline bool amdgpu_dm_vrr_active(struct dm_crtc_state *dm_state)
 	       dm_state->freesync_config.state == VRR_STATE_ACTIVE_FIXED;
 }
 
+static inline bool is_dc_timing_adjust_needed(struct dm_crtc_state *old_state,
+					      struct dm_crtc_state *new_state)
+{
+	if (new_state->freesync_config.state ==  VRR_STATE_ACTIVE_FIXED)
+		return true;
+	else if (amdgpu_dm_vrr_active(old_state) != amdgpu_dm_vrr_active(new_state))
+		return true;
+	else
+		return false;
+}
+
 /**
  * dm_pflip_high_irq() - Handle pageflip interrupt
  * @interrupt_params: ignored
@@ -4993,19 +5007,16 @@ static void fill_stream_properties_from_drm_display_mode(
 		timing_out->hdmi_vic = hv_frame.vic;
 	}
 
-	timing_out->h_addressable = mode_in->crtc_hdisplay;
-	timing_out->h_total = mode_in->crtc_htotal;
-	timing_out->h_sync_width =
-		mode_in->crtc_hsync_end - mode_in->crtc_hsync_start;
-	timing_out->h_front_porch =
-		mode_in->crtc_hsync_start - mode_in->crtc_hdisplay;
-	timing_out->v_total = mode_in->crtc_vtotal;
-	timing_out->v_addressable = mode_in->crtc_vdisplay;
-	timing_out->v_front_porch =
-		mode_in->crtc_vsync_start - mode_in->crtc_vdisplay;
-	timing_out->v_sync_width =
-		mode_in->crtc_vsync_end - mode_in->crtc_vsync_start;
-	timing_out->pix_clk_100hz = mode_in->crtc_clock * 10;
+	timing_out->h_addressable = mode_in->hdisplay;
+	timing_out->h_total = mode_in->htotal;
+	timing_out->h_sync_width = mode_in->hsync_end - mode_in->hsync_start;
+	timing_out->h_front_porch = mode_in->hsync_start - mode_in->hdisplay;
+	timing_out->v_total = mode_in->vtotal;
+	timing_out->v_addressable = mode_in->vdisplay;
+	timing_out->v_front_porch = mode_in->vsync_start - mode_in->vdisplay;
+	timing_out->v_sync_width = mode_in->vsync_end - mode_in->vsync_start;
+	timing_out->pix_clk_100hz = mode_in->clock * 10;
+
 	timing_out->aspect_ratio = get_aspect_ratio(mode_in);
 
 	stream->output_color_space = get_output_color_space(timing_out);
@@ -5225,6 +5236,33 @@ get_highest_refresh_rate_mode(struct amdgpu_dm_connector *aconnector,
 	return m_pref;
 }
 
+static bool is_freesync_video_mode(struct drm_display_mode *mode,
+				   struct amdgpu_dm_connector *aconnector)
+{
+	struct drm_display_mode *high_mode;
+	int timing_diff;
+
+	high_mode = get_highest_refresh_rate_mode(aconnector, false);
+	if (!high_mode || !mode)
+		return false;
+
+	timing_diff = high_mode->vtotal - mode->vtotal;
+
+	if (high_mode->clock == 0 || high_mode->clock != mode->clock ||
+	    high_mode->hdisplay != mode->hdisplay ||
+	    high_mode->vdisplay != mode->vdisplay ||
+	    high_mode->hsync_start != mode->hsync_start ||
+	    high_mode->hsync_end != mode->hsync_end ||
+	    high_mode->htotal != mode->htotal ||
+	    high_mode->hskew != mode->hskew ||
+	    high_mode->vscan != mode->vscan ||
+	    high_mode->vsync_start - mode->vsync_start != timing_diff ||
+	    high_mode->vsync_end - mode->vsync_end != timing_diff)
+		return false;
+	else
+		return true;
+}
+
 static struct dc_stream_state *
 create_stream_for_sink(struct amdgpu_dm_connector *aconnector,
 		       const struct drm_display_mode *drm_mode,
@@ -5238,8 +5276,10 @@ create_stream_for_sink(struct amdgpu_dm_connector *aconnector,
 		dm_state ? &dm_state->base : NULL;
 	struct dc_stream_state *stream = NULL;
 	struct drm_display_mode mode = *drm_mode;
+	struct drm_display_mode saved_mode;
+	struct drm_display_mode *freesync_mode = NULL;
 	bool native_mode_found = false;
-	bool scale = dm_state ? (dm_state->scaling != RMX_OFF) : false;
+	bool recalculate_timing = dm_state ? (dm_state->scaling != RMX_OFF) : false;
 	int mode_refresh;
 	int preferred_refresh = 0;
 #if defined(CONFIG_DRM_AMD_DC_DCN)
@@ -5247,6 +5287,9 @@ create_stream_for_sink(struct amdgpu_dm_connector *aconnector,
 	uint32_t link_bandwidth_kbps;
 #endif
 	struct dc_sink *sink = NULL;
+
+	memset(&saved_mode, 0, sizeof(saved_mode));
+
 	if (aconnector == NULL) {
 		DRM_ERROR("aconnector is NULL!\n");
 		return stream;
@@ -5298,26 +5341,39 @@ create_stream_for_sink(struct amdgpu_dm_connector *aconnector,
 		 * and the modelist may not be filled in in time.
 		 */
 		DRM_DEBUG_DRIVER("No preferred mode found\n");
+	} else {
+		recalculate_timing |= amdgpu_freesync_vid_mode &&
+				 is_freesync_video_mode(&mode, aconnector);
+		if (recalculate_timing) {
+			freesync_mode = get_highest_refresh_rate_mode(aconnector, false);
+			saved_mode = mode;
+			mode = *freesync_mode;
 		} else {
 			decide_crtc_timing_for_drm_display_mode(
 				&mode, preferred_mode,
 				dm_state ? (dm_state->scaling != RMX_OFF) : false);
+		}
+
 		preferred_refresh = drm_mode_vrefresh(preferred_mode);
 	}
 
-	if (!dm_state)
+	if (recalculate_timing)
+		drm_mode_set_crtcinfo(&saved_mode, 0);
+	else
 		drm_mode_set_crtcinfo(&mode, 0);
 
        /*
 	* If scaling is enabled and refresh rate didn't change
 	* we copy the vic and polarities of the old timings
 	*/
-	if (!scale || mode_refresh != preferred_refresh)
-		fill_stream_properties_from_drm_display_mode(stream,
-			&mode, &aconnector->base, con_state, NULL, requested_bpc);
+	if (!recalculate_timing || mode_refresh != preferred_refresh)
+		fill_stream_properties_from_drm_display_mode(
+			stream, &mode, &aconnector->base, con_state, NULL,
+			requested_bpc);
 	else
-		fill_stream_properties_from_drm_display_mode(stream,
-			&mode, &aconnector->base, con_state, old_stream, requested_bpc);
+		fill_stream_properties_from_drm_display_mode(
+			stream, &mode, &aconnector->base, con_state, old_stream,
+			requested_bpc);
 
 	stream->timing.flags.DSC = 0;
 
@@ -7802,9 +7858,22 @@ static void update_stream_irq_parameters(
 	if (new_crtc_state->vrr_supported &&
 	    config.min_refresh_in_uhz &&
 	    config.max_refresh_in_uhz) {
+		/*
+		 * if freesync compatible mode was set, config.state will be set
+		 * in atomic check
+		 */
+		if (config.state == VRR_STATE_ACTIVE_FIXED && config.fixed_refresh_in_uhz &&
+		    (!drm_atomic_crtc_needs_modeset(&new_crtc_state->base) ||
+		     new_crtc_state->freesync_config.state == VRR_STATE_ACTIVE_FIXED)) {
+			vrr_params.max_refresh_in_uhz = config.max_refresh_in_uhz;
+			vrr_params.min_refresh_in_uhz = config.min_refresh_in_uhz;
+			vrr_params.fixed_refresh_in_uhz = config.fixed_refresh_in_uhz;
+			vrr_params.state = VRR_STATE_ACTIVE_FIXED;
+		} else {
 			config.state = new_crtc_state->base.vrr_enabled ?
 						     VRR_STATE_ACTIVE_VARIABLE :
 						     VRR_STATE_INACTIVE;
+		}
 	} else {
 		config.state = VRR_STATE_UNSUPPORTED;
 	}
@@ -8125,8 +8194,7 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state,
 		 * re-adjust the min/max bounds now that DC doesn't handle this
 		 * as part of commit.
 		 */
-		if (amdgpu_dm_vrr_active(dm_old_crtc_state) !=
-		    amdgpu_dm_vrr_active(acrtc_state)) {
+		if (is_dc_timing_adjust_needed(dm_old_crtc_state, acrtc_state)) {
 			spin_lock_irqsave(&pcrtc->dev->event_lock, flags);
 			dc_stream_adjust_vmin_vmax(
 				dm->dc, acrtc_state->stream,
@@ -8411,6 +8479,7 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
 			/* i.e. reset mode */
 			if (dm_old_crtc_state->stream)
 				remove_stream(adev, acrtc, dm_old_crtc_state->stream);
+
 			mode_set_reset_required = true;
 		}
 	} /* for_each_crtc_in_state() */
@@ -8809,6 +8878,7 @@ static void get_freesync_config_for_crtc(
 			to_amdgpu_dm_connector(new_con_state->base.connector);
 	struct drm_display_mode *mode = &new_crtc_state->base.mode;
 	int vrefresh = drm_mode_vrefresh(mode);
+	bool fs_vid_mode = false;
 
 	new_crtc_state->vrr_supported = new_con_state->freesync_capable &&
 					vrefresh >= aconnector->min_vfreq &&
@@ -8816,17 +8886,24 @@ static void get_freesync_config_for_crtc(
 
 	if (new_crtc_state->vrr_supported) {
 		new_crtc_state->stream->ignore_msa_timing_param = true;
-		config.state = new_crtc_state->base.vrr_enabled ?
-				VRR_STATE_ACTIVE_VARIABLE :
-				VRR_STATE_INACTIVE;
-		config.min_refresh_in_uhz =
-				aconnector->min_vfreq * 1000000;
-		config.max_refresh_in_uhz =
-				aconnector->max_vfreq * 1000000;
+		fs_vid_mode = new_crtc_state->freesync_config.state == VRR_STATE_ACTIVE_FIXED;
+
+		config.min_refresh_in_uhz = aconnector->min_vfreq * 1000000;
+		config.max_refresh_in_uhz = aconnector->max_vfreq * 1000000;
 		config.vsif_supported = true;
 		config.btr = true;
-	}
 
+		if (fs_vid_mode) {
+			config.state = VRR_STATE_ACTIVE_FIXED;
+			config.fixed_refresh_in_uhz = new_crtc_state->freesync_config.fixed_refresh_in_uhz;
+			goto out;
+		} else if (new_crtc_state->base.vrr_enabled) {
+			config.state = VRR_STATE_ACTIVE_VARIABLE;
+		} else {
+			config.state = VRR_STATE_INACTIVE;
+		}
+	}
+out:
 	new_crtc_state->freesync_config = config;
 }
 
@@ -8839,6 +8916,50 @@ static void reset_freesync_config_for_crtc(
 	       sizeof(new_crtc_state->vrr_infopacket));
 }
 
+static bool
+is_timing_unchanged_for_freesync(struct drm_crtc_state *old_crtc_state,
+				 struct drm_crtc_state *new_crtc_state)
+{
+	struct drm_display_mode old_mode, new_mode;
+
+	if (!old_crtc_state || !new_crtc_state)
+		return false;
+
+	old_mode = old_crtc_state->mode;
+	new_mode = new_crtc_state->mode;
+
+	if (old_mode.clock       == new_mode.clock &&
+	    old_mode.hdisplay    == new_mode.hdisplay &&
+	    old_mode.vdisplay    == new_mode.vdisplay &&
+	    old_mode.htotal      == new_mode.htotal &&
+	    old_mode.vtotal      != new_mode.vtotal &&
+	    old_mode.hsync_start == new_mode.hsync_start &&
+	    old_mode.vsync_start != new_mode.vsync_start &&
+	    old_mode.hsync_end   == new_mode.hsync_end &&
+	    old_mode.vsync_end   != new_mode.vsync_end &&
+	    old_mode.hskew       == new_mode.hskew &&
+	    old_mode.vscan       == new_mode.vscan &&
+	    (old_mode.vsync_end - old_mode.vsync_start) ==
+	    (new_mode.vsync_end - new_mode.vsync_start))
+		return true;
+
+	return false;
+}
+
+static void set_freesync_fixed_config(struct dm_crtc_state *dm_new_crtc_state) {
+	uint64_t num, den, res;
+	struct drm_crtc_state *new_crtc_state = &dm_new_crtc_state->base;
+
+	dm_new_crtc_state->freesync_config.state = VRR_STATE_ACTIVE_FIXED;
+
+	num = (unsigned long long)new_crtc_state->mode.clock * 1000 * 1000000;
+	den = (unsigned long long)new_crtc_state->mode.htotal *
+	      (unsigned long long)new_crtc_state->mode.vtotal;
+
+	res = div_u64(num, den);
+	dm_new_crtc_state->freesync_config.fixed_refresh_in_uhz = res;
+}
+
 static int dm_update_crtc_state(struct amdgpu_display_manager *dm,
 				struct drm_atomic_state *state,
 				struct drm_crtc *crtc,
@@ -8929,6 +9050,11 @@ static int dm_update_crtc_state(struct amdgpu_display_manager *dm,
 		 * TODO: Refactor this function to allow this check to work
 		 * in all conditions.
 		 */
+		if (amdgpu_freesync_vid_mode &&
+		    dm_new_crtc_state->stream &&
+		    is_timing_unchanged_for_freesync(new_crtc_state, old_crtc_state))
+			goto skip_modeset;
+
 		if (dm_new_crtc_state->stream &&
 		    dc_is_stream_unchanged(new_stream, dm_old_crtc_state->stream) &&
 		    dc_is_stream_scaling_unchanged(new_stream, dm_old_crtc_state->stream)) {
@@ -8960,6 +9086,24 @@ static int dm_update_crtc_state(struct amdgpu_display_manager *dm,
 		if (!dm_old_crtc_state->stream)
 			goto skip_modeset;
 
+		if (amdgpu_freesync_vid_mode && dm_new_crtc_state->stream &&
+		    is_timing_unchanged_for_freesync(new_crtc_state,
+						     old_crtc_state)) {
+			new_crtc_state->mode_changed = false;
+			DRM_DEBUG_DRIVER(
+				"Mode change not required for front porch change, "
+				"setting mode_changed to %d",
+				new_crtc_state->mode_changed);
+
+			set_freesync_fixed_config(dm_new_crtc_state);
+
+			goto skip_modeset;
+		} else if (amdgpu_freesync_vid_mode && aconnector &&
+			   is_freesync_video_mode(&new_crtc_state->mode,
+						  aconnector)) {
+			set_freesync_fixed_config(dm_new_crtc_state);
+		}
+
 		ret = dm_atomic_get_state(state, &dm_state);
 		if (ret)
 			goto fail;