[PATCH 2/7] drm/i915/backlight: Use proper interface based on eDP version

[Murthy, Arun R]

> eDP is supposed to use VESA interface when using revision 1.5 and above, use
> Intel interface for backlight control otherwise. Add check to use correct
> interface.
> 
> Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
> Tested-by: Ben Kao <ben.kao at intel.com>
> ---
Reviewed-by: Arun R Murthy <arun.r.murthy at intel.com>

Thanks and Regards,
Arun R Murthy
--------------------

>  drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> 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 c846ef4acf5b..09e82f24d030 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> @@ -604,6 +604,7 @@ static const struct intel_panel_bl_funcs
> intel_dp_vesa_bl_funcs = {  int intel_dp_aux_init_backlight_funcs(struct
> intel_connector *connector)  {
>  	struct intel_display *display = to_intel_display(connector);
> +	struct intel_dp *intel_dp = intel_attached_dp(connector);
>  	struct drm_device *dev = connector->base.dev;
>  	struct intel_panel *panel = &connector->panel;
>  	bool try_intel_interface = false, try_vesa_interface = false; @@ -640,6
> +641,10 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector
> *connector)
>  		break;
>  	}
> 
> +	/* For eDP 1.5 and above we are supposed to use VESA interface for
> brightness control */
> +	if (intel_dp->edp_dpcd[0] >= DP_EDP_15)
> +		try_vesa_interface = true;
> +
>  	/*
>  	 * Since Intel has their own backlight control interface, the majority of
> machines out there
>  	 * using DPCD backlight controls with Intel GPUs will be using this
> interface as opposed to @@ -653,7 +658,8 @@ int
> intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
>  	 * backlight interface at all. This means that the only sensible way for us
> to detect both
>  	 * interfaces is to probe for Intel's first, and VESA's second.
>  	 */
> -	if (try_intel_interface &&
> intel_dp_aux_supports_hdr_backlight(connector)) {
> +	if (try_intel_interface &&
> intel_dp_aux_supports_hdr_backlight(connector) &&
> +	    intel_dp->edp_dpcd[0] <= DP_EDP_14b) {
>  		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Using Intel
> proprietary eDP backlight controls\n",
>  			    connector->base.base.id, connector->base.name);
>  		panel->backlight.funcs = &intel_dp_hdr_bl_funcs;
> --
> 2.34.1