diff options
| -rw-r--r-- | drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c index 345eed641455..5d4db5f8a165 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c @@ -59,8 +59,25 @@ static u32 intel_dp_aux_get_backlight(struct intel_connector *connector) { struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder); u8 read_val[2] = { 0x0 }; + u8 mode_reg; u16 level = 0; + if (drm_dp_dpcd_readb(&intel_dp->aux, + DP_EDP_BACKLIGHT_MODE_SET_REGISTER, + &mode_reg) != 1) { + DRM_DEBUG_KMS("Failed to read the DPCD register 0x%x\n", + DP_EDP_BACKLIGHT_MODE_SET_REGISTER); + return 0; + } + + /* + * If we're not in DPCD control mode yet, the programmed brightness + * value is meaningless and we should assume max brightness + */ + if ((mode_reg & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) != + DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD) + return connector->panel.backlight.max; + if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB, &read_val, sizeof(read_val)) < 0) { DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n", |