[PATCH 8/9] drm/i915/wcl: C10 phy connected to port A and B

[Taylor, Clinton A]

On Tue, 2025-06-10 at 08:13 -0700, Matt Roper wrote:
> On Tue, Jun 10, 2025 at 06:49:01AM -0700, Bhadane, Dnyaneshwar wrote:
> > 
> > 
> > > -----Original Message-----
> > > From: Roper, Matthew D <matthew.d.roper at intel.com>
> > > Sent: Monday, June 9, 2025 8:35 PM
> > > To: Bhadane, Dnyaneshwar <dnyaneshwar.bhadane at intel.com>
> > > Cc: intel-xe at lists.freedesktop.org
> > > Subject: Re: [PATCH 8/9] drm/i915/wcl: C10 phy connected to port
> > > A and B
> > > 
> > > On Sat, Jun 07, 2025 at 01:21:03AM +0530, Dnyaneshwar Bhadane
> > > wrote:
> > > > WCL added a c10 phy connected to port B. PTL code is currently
> > > > restricting c10 to phy_a only.
> > > 
> > > This seems like it's a characteristic of the platform rather than
> > > the IP itself.  We
> > > should probably go ahead and break WCL out into its own display
> > > platform that
> > > we can match against rather than assuming WCL only uses display
> > > 30.02 and
> > > vice-versa.  Or maybe we can just update the existing PTL
> > > condition if this
> > > function would never be called on PTL with a non-existent PHY B?
> > Hi Matt, 
> > 1. We could add the WCL as display platform. But for now, there is
> > not much reason to add the WCL display platform define for single
> > instance. Thoughts ?
> > 
> > 2. We could not extend the condition directly with display-
> > >platform.pantherlake && phy < PHY_C as it will wrongly select the
> > c10 PHY type for the PTL itself.
> 
> What do you mean here?  If there's no PHY B at all on PTL (based on
> 72571), then this function should never get called with phy == PHY_B,
> right?

This function is called for very PHY. This function is the only way to
determine in the PHY is C10 or C20.

> 
> >         
> >         But can be done
> >                  if ((display->platform.pantherlake && phy ==
> > PHY_A) ||
> >                  ((DISPLAY_VERx100(display) == 3002) && phy ==
> > PHY_B) )
> >                         return true;
> 
> The PHY types are a characteristic of the platform, not the display
> IP.
> So we want to try to avoid using DISPLAY_VER checks since then we'd
> do
> the wrong thing if this IP gets re-used on a platform with different
> PHY
> configuration, or if other WCL SKUs show up at some point with a
> display
> IP other than 30.02.

If this is the case, we need to make a new INTEL_DISPLAY_DEVICE for
WCL. Currently WCL shows up as a PTL to the driver.

Clint

> 
> 
> Matt
> 
> > 
> > Dnyaneshwar, 
> > > 
> > > 
> > > Matt
> > > 
> > > > 
> > > > Signed-off-by: Dnyaneshwar Bhadane
> > > > <dnyaneshwar.bhadane at intel.com>
> > > > ---
> > > >  drivers/gpu/drm/i915/display/intel_cx0_phy.c | 3 +++
> > > >  1 file changed, 3 insertions(+)
> > > > 
> > > > diff --git a/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> > > > b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> > > > index 75caccb65513..59eee0edef79 100644
> > > > --- a/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> > > > +++ b/drivers/gpu/drm/i915/display/intel_cx0_phy.c
> > > > @@ -40,6 +40,9 @@ bool intel_encoder_is_c10phy(struct
> > > > intel_encoder
> > > *encoder)
> > > >         struct intel_display *display =
> > > > to_intel_display(encoder);
> > > >         enum phy phy = intel_encoder_to_phy(encoder);
> > > > 
> > > > +       if ((DISPLAY_VERx100(display) == 3002) && phy < PHY_C)
> > > > +               return true;
> > > > +
> > > >         if (display->platform.pantherlake && phy == PHY_A)
> > > >                 return true;
> > > > 
> > > > --
> > > > 2.34.1
> > > > 
> > > 
> > > --
> > > Matt Roper
> > > Graphics Software Engineer
> > > Linux GPU Platform Enablement
> > > Intel Corporation
>