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

[Matt Roper]

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?

> 	
> 	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.


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

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation