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: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 9f5148ac..0161d94 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -4416,16 +4416,8 @@
 	/* 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 @@
 		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;