drm/i915: Split intel_ddi_compute_min_voltage_level() into platform variants

The mess inside intel_ddi_compute_min_voltage_level() is illegible.
Clean it up a bit by splitting the internals into per-platform
functions.

TODO: make it a vfunc?

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231128115138.13238-7-ville.syrjala@linux.intel.com
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>

Author: vsyrjala

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

@@ -3672,16 +3672,39 @@ static bool intel_ddi_is_audio_enabled(struct drm_i915_private *dev_priv,
 		AUDIO_OUTPUT_ENABLE(cpu_transcoder);
 }
 
+static int tgl_ddi_min_voltage_level(const struct intel_crtc_state *crtc_state)
+{
+	if (crtc_state->port_clock > 594000)
+		return 2;
+	else
+		return 0;
+}
+
+static int jsl_ddi_min_voltage_level(const struct intel_crtc_state *crtc_state)
+{
+	if (crtc_state->port_clock > 594000)
+		return 3;
+	else
+		return 0;
+}
+
+static int icl_ddi_min_voltage_level(const struct intel_crtc_state *crtc_state)
+{
+	if (crtc_state->port_clock > 594000)
+		return 1;
+	else
+		return 0;
+}
+
 void intel_ddi_compute_min_voltage_level(struct drm_i915_private *dev_priv,
 					 struct intel_crtc_state *crtc_state)
 {
-	if (DISPLAY_VER(dev_priv) >= 12 && crtc_state->port_clock > 594000)
-		crtc_state->min_voltage_level = 2;
-	else if ((IS_JASPERLAKE(dev_priv) || IS_ELKHARTLAKE(dev_priv)) &&
-		 crtc_state->port_clock > 594000)
-		crtc_state->min_voltage_level = 3;
-	else if (DISPLAY_VER(dev_priv) >= 11 && crtc_state->port_clock > 594000)
-		crtc_state->min_voltage_level = 1;
+	if (DISPLAY_VER(dev_priv) >= 12)
+		crtc_state->min_voltage_level = tgl_ddi_min_voltage_level(crtc_state);
+	else if (IS_JASPERLAKE(dev_priv) || IS_ELKHARTLAKE(dev_priv))
+		crtc_state->min_voltage_level = jsl_ddi_min_voltage_level(crtc_state);
+	else if (DISPLAY_VER(dev_priv) >= 11)
+		crtc_state->min_voltage_level = icl_ddi_min_voltage_level(crtc_state);
 }
 
 static enum transcoder bdw_transcoder_master_readout(struct drm_i915_private *dev_priv,