[PATCH 2/2] drm/i915/dp: Leave the AUX block powered on for MST

[Lyude Paul]

Acked-by: Lyude Paul <lyude at redhat.com>

On Thu, 2017-08-10 at 18:16 -0700, Dhinakaran Pandiyan wrote:
> Dell monitor with a built-in MST branch does not light up on boot
> when
> connected to a Thinkpad dock. The monitor also does not wake up after
> Suspend-to-Idle or dpms off in this configuration. Keeping the AUX
> powered up in the D3 power state solved this problem.
> 
> This partially fixes
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90963
> 
> Cc: Ethan Hsieh <ethan.hsieh at canonical.com>
> Cc: Lyude <cpaul at redhat.com>
> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c
> b/drivers/gpu/drm/i915/intel_dp.c
> index 76c8a0b..5595367 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -2485,7 +2485,11 @@ void intel_dp_sink_dpms(struct intel_dp
> *intel_dp, int mode)
>  		return;
>  
>  	if (mode != DRM_MODE_DPMS_ON) {
> -		ret = drm_dp_dpcd_writeb(&intel_dp->aux,
> DP_SET_POWER,
> +		if (intel_dp->is_mst)
> +			ret = drm_dp_dpcd_writeb(&intel_dp->aux,
> DP_SET_POWER,
> +					 DP_SET_POWER_D3_AUX_ON);
> +		else
> +			ret = drm_dp_dpcd_writeb(&intel_dp->aux,
> DP_SET_POWER,
>  					 DP_SET_POWER_D3);
>  	} else {
>  		struct intel_lspcon *lspcon =
> dp_to_lspcon(intel_dp);
-- 
Cheers,
	Lyude