Re: [PATCH] drm/i915/display: Extend i915_display_info with Type-C port details

["Almahallawy, Khaled" <khaled.almahallawy@intel.com>]

On Fri, 2025-09-26 at 11:45 +0300, Jani Nikula wrote:
> On Fri, 26 Sep 2025, Ville Syrjälä <ville.syrjala@linux.intel.com>
> wrote:
> > On Thu, Sep 25, 2025 at 04:51:53PM -0700, Khaled Almahallawy wrote:
> > > Expose key Type-C port data in i915_display_info to make it
> > > easier to
> > > understand the port configuration and active mode, especially
> > > whether
> > > the link is in DP-Alt or TBT-Alt, without having to scan kernel
> > > logs.
> > > 
> > > Tested in DP-Alt, TBT-Alt, SST, and MST.
> > > 
> > > Expected output:
> > > 
> > > [CONNECTOR:290:DP-2]: status: connected
> > > 	TC Port: E/TC#2 mode: tbt-alt pin assignment: - max
> > > lanes: 4
> > > 	physical dimensions: 600x340mm
> > > ...
> > > [CONNECTOR:263:DP-5]: status: connected
> > > 	TC Port: G/TC#4 mode: dp-alt pin assignment: C max
> > > lanes: 4
> > > 	physical dimensions: 610x350mm
> > > 
> > > Cc: Imre Deak <imre.deak@intel.com>
> > > Cc: Jani Nikula <jani.nikula@intel.com>
> > > Signed-off-by: Khaled Almahallawy <khaled.almahallawy@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_display_debugfs.c |  4 ++++
> > >  drivers/gpu/drm/i915/display/intel_tc.c              | 10
> > > ++++++++++
> > >  drivers/gpu/drm/i915/display/intel_tc.h              |  3 +++
> > >  3 files changed, 17 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > > b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > > index 10dddec3796f..6687fc18e1f5 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> > > @@ -47,6 +47,7 @@
> > >  #include "intel_psr_regs.h"
> > >  #include "intel_vdsc.h"
> > >  #include "intel_wm.h"
> > > +#include "intel_tc.h"
> > >  
> > >  static struct intel_display *node_to_intel_display(struct
> > > drm_info_node *node)
> > >  {
> > > @@ -254,6 +255,9 @@ static void intel_connector_info(struct
> > > seq_file *m,
> > >  	if (connector->status == connector_status_disconnected)
> > >  		return;
> > >  
> > > +	if
> > > (intel_encoder_is_tc(intel_attached_encoder(intel_connector)))
> > > +		intel_tc_info(m,
> > > intel_attached_dig_port(intel_connector));
> > > +
> > >  	seq_printf(m, "\tphysical dimensions: %dx%dmm\n",
> > >  		   connector->display_info.width_mm,
> > >  		   connector->display_info.height_mm);
> > > diff --git a/drivers/gpu/drm/i915/display/intel_tc.c
> > > b/drivers/gpu/drm/i915/display/intel_tc.c
> > > index c4a5601c5107..4cd7ccac28b7 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_tc.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_tc.c
> > > @@ -1703,6 +1703,16 @@ void intel_tc_port_sanitize_mode(struct
> > > intel_digital_port *dig_port,
> > >  	mutex_unlock(&tc->lock);
> > >  }
> > >  
> > > +void intel_tc_info(struct seq_file *m,  struct
> > > intel_digital_port *dig_port)
> > 
> > Please use drm_printer instead of seq_file so this can be reused
> > elsewhere.
> 
> Yeah.

Sure will do that and send V2
> 
> I'm also really not a big fan of throwing everything into
> i915_display_info. The general idea of debugfs is to have individual
> files for individual things, not to have one massive thing that
> includes
> everything, in a loop across crtcs and connectors.
> 
> I get that one file is a convenience, but at some point we have to
> say
> too much is just too much. I think so far we've just added everything
> indiscriminately.
> 
> I think it's a bit wild that we don't even have per crtc debugfs file
> for intel_crtc_info, or per connector file for intel_connector_info,
> or
> most of the individual parts in them.
> 
> Anyway, it's a bit difficult to claim this is the straw that breaks
> the
> camel's back, but I think at some point this whole thing needs an
> overhaul.
> 
That would be highly beneficial to have more focused debugfs,
particularly for TCSS and TBT. This patch driven by the need to
troubleshoot TBT-related issues without solely depending on the
following tool: 
https://github.com/intel/tbtools

Thank You for your reviews. 

~Khaled

> 
> 
> BR,
> Jani.
> 
> 
> > 
> > > +{
> > > +	struct intel_tc_port *tc = to_tc_port(dig_port);
> > > +
> > > +	seq_printf(m, "\tTC Port: %s mode: %s pin assignment: %c
> > > max lanes: %d\n", tc->port_name,
> > > +		   tc_port_mode_name(tc->mode),
> > > +		   pin_assignment_name(tc->pin_assignment),
> > > +		   tc->max_lane_count);
> > > +}
> > > +
> > >  /*
> > >   * The type-C ports are different because even when they are
> > > connected, they may
> > >   * not be available/usable by the graphics driver: see the
> > > comment on
> > > diff --git a/drivers/gpu/drm/i915/display/intel_tc.h
> > > b/drivers/gpu/drm/i915/display/intel_tc.h
> > > index fff8b96e4972..3e983d1cc0b8 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_tc.h
> > > +++ b/drivers/gpu/drm/i915/display/intel_tc.h
> > > @@ -7,6 +7,7 @@
> > >  #define __INTEL_TC_H__
> > >  
> > >  #include <linux/types.h>
> > > +#include <linux/seq_file.h>
> > >  
> > >  struct intel_crtc_state;
> > >  struct intel_digital_port;
> > > @@ -113,4 +114,6 @@ void intel_tc_port_cleanup(struct
> > > intel_digital_port *dig_port);
> > >  
> > >  bool intel_tc_cold_requires_aux_pw(struct intel_digital_port
> > > *dig_port);
> > >  
> > > +void intel_tc_info(struct seq_file *m,  struct
> > > intel_digital_port *dig_port);
> > > +
> > >  #endif /* __INTEL_TC_H__ */
> > > -- 
> > > 2.43.0
>