Re: [PATCH] drm/xe/dp: Enable DP tunneling

[Imre Deak <imre.deak@intel.com>]

On Mon, Jan 13, 2025 at 06:38:34PM +0200, Jani Nikula wrote:
> On Mon, 13 Jan 2025, Imre Deak <imre.deak@intel.com> wrote:
> > Enable the DP tunneling functionality in the xe driver.
> >
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_dp_tunnel.h |  5 +++--
> >  drivers/gpu/drm/xe/Kconfig                     | 14 ++++++++++++++
> >  drivers/gpu/drm/xe/Makefile                    |  3 +++
> >  3 files changed, 20 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_dp_tunnel.h b/drivers/gpu/drm/i915/display/intel_dp_tunnel.h
> > index e9314cf25a193..7a91b4945eb8d 100644
> > --- a/drivers/gpu/drm/i915/display/intel_dp_tunnel.h
> > +++ b/drivers/gpu/drm/i915/display/intel_dp_tunnel.h
> > @@ -20,7 +20,8 @@ struct intel_dp;
> >  struct intel_encoder;
> >  struct intel_link_bw_limits;
> >  
> > -#if IS_ENABLED(CONFIG_DRM_I915_DP_TUNNEL) && defined(I915)
> > +#if (defined(CONFIG_DRM_I915_DP_TUNNEL) && defined(I915)) || \
> > +	(defined(CONFIG_DRM_XE_DP_TUNNEL) && !defined(I915))
> 
> Please retain IS_ENABLED for checking kconfig symbols.

Ok, missed that, will change it.

> >  int intel_dp_tunnel_detect(struct intel_dp *intel_dp, struct drm_modeset_acquire_ctx *ctx);
> >  void intel_dp_tunnel_disconnect(struct intel_dp *intel_dp);
> > @@ -127,6 +128,6 @@ intel_dp_tunnel_mgr_init(struct intel_display *display)
> >  
> >  static inline void intel_dp_tunnel_mgr_cleanup(struct intel_display *display) {}
> >  
> > -#endif /* CONFIG_DRM_I915_DP_TUNNEL */
> > +#endif /* CONFIG_DRM_I915_DP_TUNNEL || CONFIG_DRM_XE_DP_TUNNEL */
> >  
> >  #endif /* __INTEL_DP_TUNNEL_H__ */
> > diff --git a/drivers/gpu/drm/xe/Kconfig b/drivers/gpu/drm/xe/Kconfig
> > index b51a2bde73e29..50cf80df51900 100644
> > --- a/drivers/gpu/drm/xe/Kconfig
> > +++ b/drivers/gpu/drm/xe/Kconfig
> > @@ -59,6 +59,20 @@ config DRM_XE_DISPLAY
> >  	help
> >  	  Disable this option only if you want to compile out display support.
> >  
> > +config DRM_XE_DP_TUNNEL
> > +	bool "Enable DP tunnel support"
> > +	depends on DRM_XE
> > +	depends on USB4
> > +	select DRM_DISPLAY_DP_TUNNEL
> > +	default y
> > +	help
> > +	  Choose this option to detect DP tunnels and enable the Bandwidth
> > +	  Allocation mode for such tunnels. This allows using the maximum
> > +	  resolution allowed by the link BW on all displays sharing the
> > +	  link BW, for instance on a Thunderbolt link.
> > +
> > +	  If in doubt say "Y".
> > +
> 
> I'm sort of wondering why we have this (and the i915 one) as
> user-selectable config options at all. Is it ever reasonable for the
> user to disable this if USB4 is enabled?

On platforms that don't support DP tunneling, while supporting other
USB4 functionality (or for systems w/o any TypeC/DP connectors) it would
make sense to disable this option.

> BR,
> Jani.
> 
> 
> >  config DRM_XE_FORCE_PROBE
> >  	string "Force probe xe for selected Intel hardware IDs"
> >  	depends on DRM_XE
> > diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> > index 5c97ad6ed7385..81f63258a7e19 100644
> > --- a/drivers/gpu/drm/xe/Makefile
> > +++ b/drivers/gpu/drm/xe/Makefile
> > @@ -301,6 +301,9 @@ ifeq ($(CONFIG_DEBUG_FS),y)
> >  		i915-display/intel_pipe_crc.o
> >  endif
> >  
> > +xe-$(CONFIG_DRM_XE_DP_TUNNEL) += \
> > +	i915-display/intel_dp_tunnel.o
> > +
> >  obj-$(CONFIG_DRM_XE) += xe.o
> >  obj-$(CONFIG_DRM_XE_KUNIT_TEST) += tests/
> 
> -- 
> Jani Nikula, Intel