[Intel-gfx] [PATCH v3 09/12] drm/i915/dp: Prevent link training fallback on disconnected port

[Govindapillai, Vinod]

On Fri, 2023-05-05 at 23:46 +0300, Imre Deak wrote:
> Prevent downgrading the link training maximum lane count/rate if the
> sink is disconnected - and so the link training failure is expected. In
> such cases modeset failures due to the reduced max link params would be
> just confusing for user space (instead of which the correct thing it
> should act on is the sink disconnect signaled by a hotplug event,
> requiring a disabling modeset).
> 
> v2:
> - Check the actual HPD state to handle the forced connector state case.
>   (Vinod)
> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Vinod Govindapillai <vinod.govindapillai at intel.com>
> Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com> (v1)
> Signed-off-by: Imre Deak <imre.deak at intel.com>
> ---

Thanks. Looks good.

Reviewed-by: Vinod Govindapillai <vinod.govindapillai at intel.com>

>  drivers/gpu/drm/i915/display/intel_dp_link_training.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> index 51d1e4b4b2f19..0952a707358c1 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> @@ -1065,6 +1065,11 @@ static void intel_dp_schedule_fallback_link_training(struct intel_dp
> *intel_dp,
>  {
>         struct intel_connector *intel_connector = intel_dp->attached_connector;
>  
> +       if (!intel_digital_port_connected(&dp_to_dig_port(intel_dp)->base)) {
> +               lt_dbg(intel_dp, DP_PHY_DPRX, "Link Training failed on disconnected sink.\n");
> +               return;
> +       }
> +
>         if (intel_dp->hobl_active) {
>                 lt_dbg(intel_dp, DP_PHY_DPRX,
>                        "Link Training failed with HOBL active, not enabling it from now on\n");