[PATCH 1/2] drm/dp_mst: Add a function to determine the mst end device

[Lin, Wayne]

[AMD Public Use]



> -----Original Message-----
> From: Lyude Paul <lyude at redhat.com>
> Sent: Wednesday, January 15, 2020 5:16 AM
> To: Lin, Wayne <Wayne.Lin at amd.com>; dri-devel at lists.freedesktop.org;
> amd-gfx at lists.freedesktop.org
> Cc: Kazlauskas, Nicholas <Nicholas.Kazlauskas at amd.com>; Wentland, Harry
> <Harry.Wentland at amd.com>; Zuo, Jerry <Jerry.Zuo at amd.com>
> Subject: Re: [PATCH 1/2] drm/dp_mst: Add a function to determine the mst end
> device
> 
> This patch series looks awesome so far, thank you for the great work! This
> patch looks great, I think we should just squash it into the next patch though
> since we don't use this function until then.
> 
Thanks for your time.
I will squash it in the new version.

> On Wed, 2020-01-08 at 16:44 +0800, Wayne Lin wrote:
> > [Why]
> > For later usage convenience, add the function
> > drm_dp_mst_is_dp_mst_end_device() to decide whether a peer device
> > connected to a DFP is mst end device. Which also indicates if the peer
> > device is capable of handling message or not.
> >
> > Signed-off-by: Wayne Lin <Wayne.Lin at amd.com>
> > ---
> >  drivers/gpu/drm/drm_dp_mst_topology.c | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> > b/drivers/gpu/drm/drm_dp_mst_topology.c
> > index eebf325d7f48..8f54b241db08 100644
> > --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> > @@ -1918,6 +1918,22 @@ static u8 drm_dp_calculate_rad(struct
> > drm_dp_mst_port *port,
> >  	return parent_lct + 1;
> >  }
> >
> > +static bool drm_dp_mst_is_dp_mst_end_device(u8 pdt, bool mcs) {
> > +	switch (pdt) {
> > +	case DP_PEER_DEVICE_DP_LEGACY_CONV:
> > +	case DP_PEER_DEVICE_SST_SINK:
> > +		return true;
> > +	case DP_PEER_DEVICE_MST_BRANCHING:
> > +		/* For sst branch device */
> > +		if (!mcs)
> > +			return true;
> > +
> > +		return false;
> > +	}
> > +	return true;
> > +}
> > +
> >  static int drm_dp_port_set_pdt(struct drm_dp_mst_port *port, u8
> > new_pdt)  {
> >  	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
> --
> Cheers,
> 	Lyude Paul
--
Best regards,
Wayne Lin