[PATCH v4 13/16] drm/i915: panel: Add get_vbt_pwm_freq() helper

[Hans de Goede <hdegoede@redhat.com>]

Factor the code which checks and drm_dbg_kms-s the VBT PWM frequency
out of get_backlight_max_vbt().

This is a preparation patch for honering the VBT PWM frequency for
devices which use an external PWM controller (devices using
pwm_setup_backlight()).

Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/gpu/drm/i915/display/intel_panel.c | 27 ++++++++++++++--------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
index 3c5056dbf607..8efdd9f08a08 100644
--- a/drivers/gpu/drm/i915/display/intel_panel.c
+++ b/drivers/gpu/drm/i915/display/intel_panel.c
@@ -1543,18 +1543,9 @@ static u32 vlv_hz_to_pwm(struct intel_connector *connector, u32 pwm_freq_hz)
 	return DIV_ROUND_CLOSEST(clock, pwm_freq_hz * mul);
 }
 
-static u32 get_backlight_max_vbt(struct intel_connector *connector)
+static u16 get_vbt_pwm_freq(struct drm_i915_private *dev_priv)
 {
-	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
-	struct intel_panel *panel = &connector->panel;
 	u16 pwm_freq_hz = dev_priv->vbt.backlight.pwm_freq_hz;
-	u32 pwm;
-
-	if (!panel->backlight.hz_to_pwm) {
-		drm_dbg_kms(&dev_priv->drm,
-			    "backlight frequency conversion not supported\n");
-		return 0;
-	}
 
 	if (pwm_freq_hz) {
 		drm_dbg_kms(&dev_priv->drm,
@@ -1567,6 +1558,22 @@ static u32 get_backlight_max_vbt(struct intel_connector *connector)
 			    pwm_freq_hz);
 	}
 
+	return pwm_freq_hz;
+}
+
+static u32 get_backlight_max_vbt(struct intel_connector *connector)
+{
+	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
+	struct intel_panel *panel = &connector->panel;
+	u16 pwm_freq_hz = get_vbt_pwm_freq(dev_priv);
+	u32 pwm;
+
+	if (!panel->backlight.hz_to_pwm) {
+		drm_dbg_kms(&dev_priv->drm,
+			    "backlight frequency conversion not supported\n");
+		return 0;
+	}
+
 	pwm = panel->backlight.hz_to_pwm(connector, pwm_freq_hz);
 	if (!pwm) {
 		drm_dbg_kms(&dev_priv->drm,
-- 
2.26.2