drm/vc4: hdmi: Move clock validation to its own function

Our code is doing the same clock rate validation in multiple instances.
Let's create a helper to share the rate validation.
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220222164042.403112-3-maxime@cerno.tech

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -1245,6 +1245,19 @@ static void vc4_hdmi_encoder_atomic_mode_set(struct drm_encoder *encoder,
 	mutex_unlock(&vc4_hdmi->mutex);
 }
 
+static enum drm_mode_status
+vc4_hdmi_encoder_clock_valid(const struct vc4_hdmi *vc4_hdmi,
+			     unsigned long long clock)
+{
+	if (clock > vc4_hdmi->variant->max_pixel_clock)
+		return MODE_CLOCK_HIGH;
+
+	if (vc4_hdmi->disable_4kp60 && clock > HDMI_14_MAX_TMDS_CLK)
+		return MODE_CLOCK_HIGH;
+
+	return MODE_OK;
+}
+
 #define WIFI_2_4GHz_CH1_MIN_FREQ	2400000000ULL
 #define WIFI_2_4GHz_CH1_MAX_FREQ	2422000000ULL
 
@@ -1288,10 +1301,7 @@ static int vc4_hdmi_encoder_atomic_check(struct drm_encoder *encoder,
 	if (mode->flags & DRM_MODE_FLAG_DBLCLK)
 		tmds_char_rate = tmds_char_rate * 2;
 
-	if (tmds_char_rate > vc4_hdmi->variant->max_pixel_clock)
-		return -EINVAL;
-
-	if (vc4_hdmi->disable_4kp60 && (tmds_char_rate > HDMI_14_MAX_TMDS_CLK))
+	if (vc4_hdmi_encoder_clock_valid(vc4_hdmi, tmds_char_rate) != MODE_OK)
 		return -EINVAL;
 
 	vc4_state->tmds_char_rate = tmds_char_rate;
@@ -1310,13 +1320,7 @@ vc4_hdmi_encoder_mode_valid(struct drm_encoder *encoder,
 	     (mode->hsync_end % 2) || (mode->htotal % 2)))
 		return MODE_H_ILLEGAL;
 
-	if ((mode->clock * 1000) > vc4_hdmi->variant->max_pixel_clock)
-		return MODE_CLOCK_HIGH;
-
-	if (vc4_hdmi->disable_4kp60 && vc4_hdmi_mode_needs_scrambling(mode))
-		return MODE_CLOCK_HIGH;
-
-	return MODE_OK;
+	return vc4_hdmi_encoder_clock_valid(vc4_hdmi, mode->clock * 1000);
 }
 
 static const struct drm_encoder_helper_funcs vc4_hdmi_encoder_helper_funcs = {