drm/i915: compute the target_clock for edp directly

... instead of abusing mode->clock by storing it in there - we
shouldn't touch that one at all. This patch is the first prep step to
constify the mode argument of the intel_dp_mode_fixup function.

The next patch will stop us from modifying mode->clock.
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -4416,16 +4416,8 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
 	/* CPU eDP doesn't require FDI link, so just set DP M/N
 	   according to current link config */
 	if (is_cpu_edp) {
-		target_clock = mode->clock;
 		intel_edp_link_config(edp_encoder, &lane, &link_bw);
 	} else {
-		/* [e]DP over FDI requires target mode clock
-		   instead of link clock */
-		if (is_dp)
-			target_clock = mode->clock;
-		else
-			target_clock = adjusted_mode->clock;
-
 		/* FDI is a binary signal running at ~2.7GHz, encoding
 		 * each output octet as 10 bits. The actual frequency
 		 * is stored as a divider into a 100MHz clock, and the
@@ -4436,6 +4428,14 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
 		link_bw = intel_fdi_link_freq(dev) * MHz(100)/KHz(1)/10;
 	}
 
+	/* [e]DP over FDI requires target mode clock instead of link clock. */
+	if (edp_encoder)
+		target_clock = intel_edp_target_clock(edp_encoder, mode);
+	else if (is_dp)
+		target_clock = mode->clock;
+	else
+		target_clock = adjusted_mode->clock;
+
 	/* determine panel color depth */
 	temp = I915_READ(PIPECONF(pipe));
 	temp &= ~PIPE_BPC_MASK;

drivers/gpu/drm/i915/intel_dp.c

@@ -152,6 +152,18 @@ intel_edp_link_config(struct intel_encoder *intel_encoder,
 		*link_bw = 270000;
 }
 
+int
+intel_edp_target_clock(struct intel_encoder *intel_encoder,
+		       struct drm_display_mode *mode)
+{
+	struct intel_dp *intel_dp = container_of(intel_encoder, struct intel_dp, base);
+
+	if (intel_dp->panel_fixed_mode)
+		return intel_dp->panel_fixed_mode->clock;
+	else
+		return mode->clock;
+}
+
 static int
 intel_dp_max_lane_count(struct intel_dp *intel_dp)
 {

drivers/gpu/drm/i915/intel_drv.h

@@ -359,6 +359,8 @@ intel_dp_set_m_n(struct drm_crtc *crtc, struct drm_display_mode *mode,
 		 struct drm_display_mode *adjusted_mode);
 extern bool intel_dpd_is_edp(struct drm_device *dev);
 extern void intel_edp_link_config(struct intel_encoder *, int *, int *);
+extern int intel_edp_target_clock(struct intel_encoder *,
+				  struct drm_display_mode *mode);
 extern bool intel_encoder_is_pch_edp(struct drm_encoder *encoder);
 extern int intel_plane_init(struct drm_device *dev, enum pipe pipe);
 extern void intel_flush_display_plane(struct drm_i915_private *dev_priv,