[RFC 2/4] drm/i915/display/dp: Dont send hotplug event on LT failure

[Murthy, Arun R]

> -----Original Message-----
> From: Nikula, Jani <jani.nikula at intel.com>
> Sent: Tuesday, February 6, 2024 5:10 PM
> To: Murthy, Arun R <arun.r.murthy at intel.com>; intel-gfx at lists.freedesktop.org
> Cc: Deak, Imre <imre.deak at intel.com>; Syrjala, Ville <ville.syrjala at intel.com>;
> Shankar, Uma <uma.shankar at intel.com>; Murthy, Arun R
> <arun.r.murthy at intel.com>
> Subject: Re: [RFC 2/4] drm/i915/display/dp: Dont send hotplug event on LT
> failure
> 
> On Tue, 06 Feb 2024, Arun R Murthy <arun.r.murthy at intel.com> wrote:
> > On link training failure fallback sequence a hotpplu event was sent to
> > the user, but this is not requried as we are not changing the mode and
> > instead only changing the link rate and lane count. User has no
> > dependency with these parameters.
> >
> > Signed-off-by: Arun R Murthy <arun.r.murthy at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_dp_link_training.c | 5 +----
> >  1 file changed, 1 insertion(+), 4 deletions(-)
> >
> > 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 1abfafbbfa75..242cb08e9fc4 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
> > @@ -1074,8 +1074,6 @@ intel_dp_link_train_phy(struct intel_dp
> > *intel_dp,  static void intel_dp_schedule_fallback_link_training(struct intel_dp
> *intel_dp,
> >  						     const struct intel_crtc_state
> *crtc_state)  {
> > -	struct intel_connector *intel_connector = intel_dp-
> >attached_connector;
> > -	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
> >
> >  	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"); @@ -1092,8 +1090,7 @@ static void
> intel_dp_schedule_fallback_link_training(struct intel_dp *intel_dp,
> >  		return;
> >  	}
> >
> > -	/* Schedule a Hotplug Uevent to userspace to start modeset */
> > -	queue_work(i915->unordered_wq, &intel_connector-
> >modeset_retry_work);
> > +	/* TODO: Re-visit, sending hotplug is not required. No need to
> > +notify user as we are not changing the mode */
> 
> Yeah, we're not changing the mode, we're asking the userspace to change the
> mode.
As far as I see mode change is not necessity. Link rate and lane count change is internal to KMD.

Thanks and Regards,
Arun R Murthy
--------------------
> 
> BR,
> Jani.
> 
> >  }
> >
> >  /* Perform the link training on all LTTPRs and the DPRX on a link. */
> 
> --
> Jani Nikula, Intel