On Tue, Oct 26, 2021 at 06:08:44PM -0400, Lyude Paul wrote:

This simply adds proper support for panel backlights that can be controlled via VESA's backlight control protocol, but which also require that we enable and disable the backlight via PWM instead of via the DPCD interface. We also enable this by default, in order to fix some people's backlights that were broken by not having this enabled.

For reference, backlights that require this and use VESA's backlight interface tend to be laptops with hybrid GPUs, but this very well may change in the future.

v4:

• Make sure that we call intel_backlight_level_to_pwm() in intel_dp_aux_vesa_enable_backlight() - vsyrjala

Signed-off-by: Lyude Paul lyude@redhat.com Link: https://gitlab.freedesktop.org/drm/intel/-/issues/3680 Fixes: fe7d52bccab6 ("drm/i915/dp: Don't use DPCD backlights that need PWM enable/disable") Cc: stable@vger.kernel.org # v5.12+

Seems consistent enough. Reviewed-by: Ville Syrjälä ville.syrjala@linux.intel.com

---

.../drm/i915/display/intel_dp_aux_backlight.c | 27 ++++++++++++++----- 1 file changed, 21 insertions(+), 6 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 569d17b4d00f..f05b71c01b8e 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c @@ -293,6 +293,13 @@ intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state, struct intel_panel *panel = &connector->panel; struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);

• if (!panel->backlight.edp.vesa.info.aux_enable) {

• u32 pwm_level = intel_backlight_invert_pwm_level(connector,
  

• 						 panel->backlight.pwm_level_max);
  

• panel->backlight.pwm_funcs->enable(crtc_state, conn_state, pwm_level);
  

• }
• drm_edp_backlight_enable(&intel_dp->aux, &panel->backlight.edp.vesa.info, level);

} @@ -304,6 +311,10 @@ static void intel_dp_aux_vesa_disable_backlight(const struct drm_connector_state struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder); drm_edp_backlight_disable(&intel_dp->aux, &panel->backlight.edp.vesa.info);

• if (!panel->backlight.edp.vesa.info.aux_enable)

• panel->backlight.pwm_funcs->disable(old_conn_state,
  

• 				    intel_backlight_invert_pwm_level(connector, 0));
  

} static int intel_dp_aux_vesa_setup_backlight(struct intel_connector *connector, enum pipe pipe) @@ -321,6 +332,15 @@ static int intel_dp_aux_vesa_setup_backlight(struct intel_connector *connector, if (ret < 0) return ret;

• if (!panel->backlight.edp.vesa.info.aux_enable) {

• ret = panel->backlight.pwm_funcs->setup(connector, pipe);
  

• if (ret < 0) {
  

• 	drm_err(&i915->drm,
  

• 		"Failed to setup PWM backlight controls for eDP backlight: %d\n",
  

• 		ret);
  

• 	return ret;
  

• }
  

• } panel->backlight.max = panel->backlight.edp.vesa.info.max; panel->backlight.min = 0; if (current_mode == DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD) {

@@ -340,12 +360,7 @@ intel_dp_aux_supports_vesa_backlight(struct intel_connector *connector) struct intel_dp *intel_dp = intel_attached_dp(connector); struct drm_i915_private *i915 = dp_to_i915(intel_dp);

• /* TODO: We currently only support AUX only backlight configurations, not backlights which

• * require a mix of PWM and AUX controls to work. In the mean time, these machines typically
  

• * work just fine using normal PWM controls anyway.
  

• */
  

• if ((intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&

•    drm_edp_backlight_supported(intel_dp->edp_dpcd)) {
  

• if (drm_edp_backlight_supported(intel_dp->edp_dpcd)) { drm_dbg_kms(&i915->drm, "AUX Backlight Control Supported!\n"); return true; }

-- 2.31.1