drm/i915: Refactor timestamping constants update

Once we do the hw vs. uapi split we can no longer use
drm_atomic_helper_calc_timestamping_constants() as it'll
consult the uapi state instead of the hw state.

So let's just update the vblank timestamping constants whenever
we update the scanline offset. We use both to convert the hw
scanline count to something which matches the software timing
values.

First I thought to put these into intel_crtc_vblank_on() but
we may want to get the scanline counter value before that (eg.
from some early tracepoints), so let's stick to updating them
a bit earlier than intel_crtc_vblank_on().
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191007114943.29307-3-ville.syrjala@linux.intel.com

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

@@ -13316,10 +13316,15 @@ intel_modeset_verify_disabled(struct drm_i915_private *dev_priv,
 	verify_disabled_dpll_state(dev_priv);
 }
 
-static void update_scanline_offset(const struct intel_crtc_state *crtc_state)
+static void
+intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state)
 {
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+	const struct drm_display_mode *adjusted_mode =
+		&crtc_state->base.adjusted_mode;
+
+	drm_calc_timestamping_constants(&crtc->base, adjusted_mode);
 
 	/*
 	 * The scanline counter increments at the leading edge of hsync.
@@ -13349,7 +13354,6 @@ static void update_scanline_offset(const struct intel_crtc_state *crtc_state)
 	 * answer that's slightly in the future.
 	 */
 	if (IS_GEN(dev_priv, 2)) {
-		const struct drm_display_mode *adjusted_mode = &crtc_state->base.adjusted_mode;
 		int vtotal;
 
 		vtotal = adjusted_mode->crtc_vtotal;
@@ -13360,8 +13364,9 @@ static void update_scanline_offset(const struct intel_crtc_state *crtc_state)
 	} else if (HAS_DDI(dev_priv) &&
 		   intel_crtc_has_type(crtc_state, INTEL_OUTPUT_HDMI)) {
 		crtc->scanline_offset = 2;
-	} else
+	} else {
 		crtc->scanline_offset = 1;
+	}
 }
 
 static void intel_modeset_clear_plls(struct intel_atomic_state *state)
@@ -13784,7 +13789,8 @@ static void intel_update_crtc(struct intel_crtc *crtc,
 						 to_intel_plane(crtc->base.primary));
 
 	if (modeset) {
-		update_scanline_offset(new_crtc_state);
+		intel_crtc_update_active_timings(new_crtc_state);
+
 		dev_priv->display.crtc_enable(new_crtc_state, state);
 
 		/* vblanks work again, re-enable pipe CRC. */
@@ -16812,9 +16818,7 @@ static void intel_modeset_readout_hw_state(struct drm_device *dev)
 			if (WARN_ON(min_cdclk < 0))
 				min_cdclk = 0;
 
-			drm_calc_timestamping_constants(&crtc->base,
-							&crtc_state->base.adjusted_mode);
-			update_scanline_offset(crtc_state);
+			intel_crtc_update_active_timings(crtc_state);
 		}
 
 		dev_priv->min_cdclk[crtc->pipe] = min_cdclk;