linux-kernel - Re: [PATCH 1/2] drm: Add HPD state to drm_connector_oob_hotplug

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Date:   Mon, 14 Feb 2022 15:47:49 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Imre Deak <imre.deak@...el.com>
Cc:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        Rob Clark <robdclark@...il.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        freedreno@...ts.freedesktop.org,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        intel-gfx@...ts.freedesktop.org, linux-usb@...r.kernel.org,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Stephen Boyd <swboyd@...omium.org>,
        dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Sean Paul <sean@...rly.run>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] drm: Add HPD state to
 drm_connector_oob_hotplug_event()

On Mon 14 Feb 09:59 PST 2022, Imre Deak wrote:

> On Mon, Feb 07, 2022 at 08:43:27PM -0800, Bjorn Andersson wrote:
> > In some implementations, such as the Qualcomm platforms, the display
> > driver has no way to query the current HPD state and as such it's
> > impossible to distinguish between disconnect and attention events.
> > 
> > Add a parameter to drm_connector_oob_hotplug_event() to pass the HPD
> > state.
> > 
> > Also push the test for unchanged state in the displayport altmode driver
> > into the i915 driver, to allow other drivers to act upon each update.
> > 
> > Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> > ---
> > 
> > Note that the Intel driver has only been compile tested with this patch.
> > 
> >  drivers/gpu/drm/drm_connector.c          |  6 ++++--
> >  drivers/gpu/drm/i915/display/intel_dp.c  | 14 +++++++++++---
> >  drivers/gpu/drm/i915/i915_drv.h          |  3 +++
> >  drivers/usb/typec/altmodes/displayport.c |  9 ++-------
> >  include/drm/drm_connector.h              |  5 +++--
> >  5 files changed, 23 insertions(+), 14 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> > index a50c82bc2b2f..ad7295597c0f 100644
> > --- a/drivers/gpu/drm/drm_connector.c
> > +++ b/drivers/gpu/drm/drm_connector.c
> > @@ -2825,6 +2825,7 @@ struct drm_connector *drm_connector_find_by_fwnode(struct fwnode_handle *fwnode)
> >  /**
> >   * drm_connector_oob_hotplug_event - Report out-of-band hotplug event to connector
> >   * @connector_fwnode: fwnode_handle to report the event on
> > + * @hpd_state: number of data lanes available
> >   *
> >   * On some hardware a hotplug event notification may come from outside the display
> >   * driver / device. An example of this is some USB Type-C setups where the hardware
> > @@ -2834,7 +2835,8 @@ struct drm_connector *drm_connector_find_by_fwnode(struct fwnode_handle *fwnode)
> >   * This function can be used to report these out-of-band events after obtaining
> >   * a drm_connector reference through calling drm_connector_find_by_fwnode().
> >   */
> > -void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode)
> > +void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode,
> > +				     bool hpd_state)
> >  {
> >  	struct drm_connector *connector;
> >  
> > @@ -2843,7 +2845,7 @@ void drm_connector_oob_hotplug_event(struct fwnode_handle *connector_fwnode)
> >  		return;
> >  
> >  	if (connector->funcs->oob_hotplug_event)
> > -		connector->funcs->oob_hotplug_event(connector);
> > +		connector->funcs->oob_hotplug_event(connector, hpd_state);
> >  
> >  	drm_connector_put(connector);
> >  }
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> > index 146b83916005..00520867d37b 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> > @@ -4816,15 +4816,23 @@ static int intel_dp_connector_atomic_check(struct drm_connector *conn,
> >  	return intel_modeset_synced_crtcs(state, conn);
> >  }
> >  
> > -static void intel_dp_oob_hotplug_event(struct drm_connector *connector)
> > +static void intel_dp_oob_hotplug_event(struct drm_connector *connector, bool hpd_state)
> >  {
> >  	struct intel_encoder *encoder = intel_attached_encoder(to_intel_connector(connector));
> >  	struct drm_i915_private *i915 = to_i915(connector->dev);
> > +	bool need_work = false;
> >  
> >  	spin_lock_irq(&i915->irq_lock);
> > -	i915->hotplug.event_bits |= BIT(encoder->hpd_pin);
> > +	if (hpd_state != i915->hotplug.oob_hotplug_state) {
> 
> hpd_state is speific to the encoder (pin) so similarly to event_bits
> oob_hotplug_state should be a bitmask as well.
> 

That makes sense, thanks for point it out!

Regards,
Bjorn