drm/i915/tv: Bypass the vertical filter if possible

vsyrjala · vsyrjala · commit 68e94f62cfbe · 2019-01-29T23:27:31.000+02:00
Let's switch the pipe into interlaced mode and switch off the TV encoder vertical filter if the pipe vdisplay matches the TV YSIZE exactly. While I didn't measure it I presume this might reduce the power consumption a little bit, and the pixel rate is halved as the pipe will now fetching in interlaced mode rather than in progressive mode (effectively the same difference as between IF-ID vs. PF-ID pfit modes on more modern hardware) so a bit easier on the memory bandwidth. Cc: Imre Deak <imre.deak@intel.com> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20190129141913.5515-2-ville.syrjala@linux.intel.com Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c
@@ -1159,6 +1159,22 @@ intel_tv_get_config(struct intel_encoder *encoder,
 			I915_MODE_FLAG_USE_SCANLINE_COUNTER;
 }
 
+static bool intel_tv_source_too_wide(struct drm_i915_private *dev_priv,
+				     int hdisplay)
+{
+	return IS_GEN(dev_priv, 3) && hdisplay > 1024;
+}
+
+static bool intel_tv_vert_scaling(const struct drm_display_mode *tv_mode,
+				  const struct drm_connector_state *conn_state,
+				  int vdisplay)
+{
+	return tv_mode->crtc_vdisplay -
+		conn_state->tv.margins.top -
+		conn_state->tv.margins.bottom !=
+		vdisplay;
+}
+
 static int
 intel_tv_compute_config(struct intel_encoder *encoder,
 			struct intel_crtc_state *pipe_config,
@@ -1189,7 +1205,8 @@ intel_tv_compute_config(struct intel_encoder *encoder,
 	intel_tv_mode_to_mode(adjusted_mode, tv_mode);
 	drm_mode_set_crtcinfo(adjusted_mode, 0);
 
-	if (IS_GEN(dev_priv, 3) && hdisplay > 1024) {
+	if (intel_tv_source_too_wide(dev_priv, hdisplay) ||
+	    !intel_tv_vert_scaling(adjusted_mode, conn_state, vdisplay)) {
 		int extra, top, bottom;
 
 		extra = adjusted_mode->crtc_vdisplay - vdisplay;
