From 73ab484c90f5a696a6552c82f5d64b13303c0813 Mon Sep 17 00:00:00 2001 From: Puthikorn Voravootivat Date: Thu, 11 May 2017 16:02:18 -0700 Subject: [PATCH] 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: Puthikorn Voravootivat Reviewed-by: Dhinakaran Pandiyan Signed-off-by: Jani Nikula Link: http://patchwork.freedesktop.org/patch/msgid/20170511230225.142870-3-puthik@chromium.org --- drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 33 +++++++++++++++---- 1 file changed, 27 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 341bf2cb0c25..870c03fc0f3a 100644 --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c @@ -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) -- 2.20.1