intel_dp_aux_enable_backlight() assumed that the register
BACKLIGHT_BRIGHTNESS_CONTROL_MODE can only has value 01
(DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET) when initialize.
This patch fixed that by handling all cases of that register.
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Signed-off-by: Puthikorn Voravootivat <puthik@xxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 29 +++++++++++++++++++++------
1 file changed, 23 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
index 42f73d9a3ccf..f06c8381c74e 100644
--- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
@@ -101,15 +101,32 @@ static void intel_dp_aux_enable_backlight(struct intel_connector *connector)
{
struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
uint8_t dpcd_buf = 0;
+ uint8_t edp_backlight_mode = 0;
set_aux_backlight_enable(intel_dp, true);
- if ((drm_dp_dpcd_readb(&intel_dp->aux,
- DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf) == 1) &&
- ((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) ==
- DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET))
- drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
- (dpcd_buf | DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD));
+ if (!drm_dp_dpcd_readb(&intel_dp->aux,
+ DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf)) {
+ return;
+ }
+
+ edp_backlight_mode = dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
+
+ switch (edp_backlight_mode) {
+ case DP_EDP_BACKLIGHT_CONTROL_MODE_PWM:
+ case DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET:
+ case DP_EDP_BACKLIGHT_CONTROL_MODE_PRODUCT:
+ dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
+ dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
+ drm_dp_dpcd_writeb(&intel_dp->aux,
+ DP_EDP_BACKLIGHT_MODE_SET_REGISTER, dpcd_buf);
+ break;
+
+ /* Do nothing when it is already DPCD mode */
+ case DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD:
+ default:
+ break;
+ }
}
static void intel_dp_aux_disable_backlight(struct intel_connector *connector)
--
2.12.1.500.gab5fba24ee-goog
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