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Commit 73ab484c authored by Puthikorn Voravootivat's avatar Puthikorn Voravootivat Committed by Jani Nikula
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drm/i915: Correctly enable backlight brightness adjustment via DPCD 



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.

Signed-off-by: default avatarPuthikorn Voravootivat <puthik@chromium.org>
Reviewed-by: default avatarDhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Signed-off-by: default avatarJani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170511230225.142870-3-puthik@chromium.org
parent a644ca9b

drivers/gpu/drm/i915/intel_dp_aux_backlight.c

+27 −6
Original line number Diff line number Diff line
@@ -97,15 +97,36 @@ 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) != 1) {

		DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",

			      DP_EDP_BACKLIGHT_MODE_SET_REGISTER);

		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;

		if (drm_dp_dpcd_writeb(&intel_dp->aux,

			DP_EDP_BACKLIGHT_MODE_SET_REGISTER, dpcd_buf) < 0) {

			DRM_DEBUG_KMS("Failed to write aux backlight mode\n");

		}

		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)