drm/i915/cdclk: Extract hsw_ips_min_cdclk()

Pull the whole BDW IPS min CDCLK stuff into the IPS code
so that all the details around IPS are contained in once
place.

Note that while
- min_cdclk = DIV_ROUND_UP(min_cdclk * 100, 95);
vs.
+ min_cdclk = max(DIV_ROUND_UP(crtc_state->pixel_rate * 100, 95), min_cdclk)
may look different, they are in fact the same because
min_cdclk==crtc_state->pixel_rate at this point in
intel_crtc_compute_min_cdclk() on BDW.

Signed-off-by: Ville Syrjälä <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Reviewed-by: Jani Nikula <[e-mail]>

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

···
 	return HAS_IPS(to_i915(crtc->base.dev)) && crtc->pipe == PIPE_A;
 }
 
-bool hsw_crtc_state_ips_capable(const struct intel_crtc_state *crtc_state)
+static bool hsw_crtc_state_ips_capable(const struct intel_crtc_state *crtc_state)
 {
 	struct intel_display *display = to_intel_display(crtc_state);
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
···
 		return false;
 
 	return true;
+}
+
+int hsw_ips_min_cdclk(const struct intel_crtc_state *crtc_state)
+{
+	struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
+
+	if (!IS_BROADWELL(i915))
+		return 0;
+
+	if (!hsw_crtc_state_ips_capable(crtc_state))
+		return 0;
+
+	/* pixel rate mustn't exceed 95% of cdclk with IPS on BDW */
+	return DIV_ROUND_UP(crtc_state->pixel_rate * 100, 95);
 }
 
 int hsw_ips_compute_config(struct intel_atomic_state *state,

drivers/gpu/drm/i915/display/hsw_ips.h

···
 void hsw_ips_post_update(struct intel_atomic_state *state,
 			 struct intel_crtc *crtc);
 bool hsw_crtc_supports_ips(struct intel_crtc *crtc);
-bool hsw_crtc_state_ips_capable(const struct intel_crtc_state *crtc_state);
+int hsw_ips_min_cdclk(const struct intel_crtc_state *crtc_state);
 int hsw_ips_compute_config(struct intel_atomic_state *state,
 			   struct intel_crtc *crtc);
 void hsw_ips_get_config(struct intel_crtc_state *crtc_state);
···
 {
 	return false;
 }
-static inline bool hsw_crtc_state_ips_capable(const struct intel_crtc_state *crtc_state)
+static inline int hsw_ips_min_cdclk(const struct intel_crtc_state *crtc_state)
 {
-	return false;
+	return 0;
 }
 static inline int hsw_ips_compute_config(struct intel_atomic_state *state,
 					 struct intel_crtc *crtc)

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

···
 		return 0;
 
 	min_cdclk = intel_pixel_rate_to_cdclk(crtc_state);
-
-	/* pixel rate mustn't exceed 95% of cdclk with IPS on BDW */
-	if (IS_BROADWELL(dev_priv) && hsw_crtc_state_ips_capable(crtc_state))
-		min_cdclk = DIV_ROUND_UP(min_cdclk * 100, 95);
+	min_cdclk = max(hsw_ips_min_cdclk(crtc_state), min_cdclk);
 
 	/* BSpec says "Do not use DisplayPort with CDCLK less than 432 MHz,
 	 * audio enabled, port width x4, and link rate HBR2 (5.4 GHz), or else