TCON tend to have better brightness scaling with lower
PWM frequency. This patch set the divider to highest
value to lower the PWM frequency.
Signed-off-by: Puthikorn Voravootivat <puthik@xxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
index 643b604be2de..32b426006a6a 100644
--- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
@@ -116,6 +116,7 @@ static void intel_dp_aux_enable_backlight(struct intel_connector *connector)
uint8_t dpcd_buf = 0;
uint8_t new_dpcd_buf = 0;
uint8_t edp_backlight_mode = 0;
+ bool freq_cap = false;
set_aux_backlight_enable(intel_dp, true);
@@ -146,10 +147,20 @@ static void intel_dp_aux_enable_backlight(struct intel_connector *connector)
intel_dp_aux_set_dynamic_backlight_percent(intel_dp, 0, 100);
}
+ /* Use highest frequency divider if supported */
+ freq_cap = intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_FREQ_AUX_SET_CAP;
+ if (freq_cap)
+ new_dpcd_buf |= DP_EDP_BACKLIGHT_FREQ_AUX_SET_ENABLE;
+
if (new_dpcd_buf != dpcd_buf) {
drm_dp_dpcd_writeb(&intel_dp->aux,
DP_EDP_BACKLIGHT_MODE_SET_REGISTER, new_dpcd_buf);
}
+
+ if (freq_cap) {
+ drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_FREQ_SET,
+ 0xff);
+ }
}
static void intel_dp_aux_disable_backlight(struct intel_connector *connector)
--
2.12.0.246.ga2ecc84866-goog
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