[Intel-gfx] [PATCH 2/3] drm/i915: use default 200 Hz backlight frequency

[Jani Nikula]

If the backlight modulation frequency can't be extracted from the
registers or from VBT, use 200 Hz as the default. This may enable
backlight on some machines that previously failed.

Signed-off-by: Jani Nikula <jani.nikula at intel.com>
---
 drivers/gpu/drm/i915/intel_panel.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index 2d1696386b0d..2b25497333de 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -1393,14 +1393,18 @@ static u32 get_backlight_max_vbt(struct intel_connector *connector)
 	u16 pwm_freq_hz = dev_priv->vbt.backlight.pwm_freq_hz;
 	u32 pwm;
 
-	if (!pwm_freq_hz) {
-		DRM_DEBUG_KMS("backlight frequency not specified in VBT\n");
+	if (!panel->backlight.hz_to_pwm) {
+		DRM_DEBUG_KMS("backlight frequency conversion not supported\n");
 		return 0;
 	}
 
-	if (!panel->backlight.hz_to_pwm) {
-		DRM_DEBUG_KMS("backlight frequency setting from VBT currently not supported on this platform\n");
-		return 0;
+	if (pwm_freq_hz) {
+		DRM_DEBUG_KMS("VBT defined backlight frequency %u Hz\n",
+			      pwm_freq_hz);
+	} else {
+		pwm_freq_hz = 200;
+		DRM_DEBUG_KMS("default backlight frequency %u Hz\n",
+			      pwm_freq_hz);
 	}
 
 	pwm = panel->backlight.hz_to_pwm(connector, pwm_freq_hz);
@@ -1409,8 +1413,6 @@ static u32 get_backlight_max_vbt(struct intel_connector *connector)
 		return 0;
 	}
 
-	DRM_DEBUG_KMS("backlight frequency %u Hz from VBT\n", pwm_freq_hz);
-
 	return pwm;
 }
 
-- 
2.1.4