[PATCH v14 03/10] drm/display: Add Type-C switch helpers

[Pin-yen Lin]

On Fri, Mar 31, 2023 at 11:36 AM Pin-yen Lin <treapking at chromium.org> wrote:
>
> Hi Andy,
>
> Thanks for the review.
>
> On Wed, Mar 22, 2023 at 8:01 PM Andy Shevchenko
> <andriy.shevchenko at linux.intel.com> wrote:
> >
> > On Wed, Mar 22, 2023 at 06:46:32PM +0800, Pin-yen Lin wrote:
> > > Add helpers to register and unregister Type-C "switches" for bridges
> > > capable of switching their output between two downstream devices.
> > >
> > > The helper registers USB Type-C mode switches when the "mode-switch"
> > > and the "reg" properties are available in Device Tree.
> >
> > ...
> >
> > > +config DRM_DISPLAY_DP_TYPEC_HELPER
> >
> > > +     bool
> > > +     default y
> >
> >         def_bool y
> >
> > > +     depends on DRM_DISPLAY_HELPER
> > > +     depends on DRM_DISPLAY_HELPER=TYPEC || TYPEC=y
> > > +     help
> > > +       DRM display helpers for USB Type-C Displayport Alternate mode.
> >
> > Hmm... Dunno if this help is enough.
>
> Okay I'll add more detail in the next version.
> >
> > ...
> >
> > > +     snprintf(name, sizeof(name), "%pfwP-%u", fwnode, port_num);
> >
> > Would it be possible to have a dup in name and would it be a problem if so?
> >
> The port_num is included in the name, so the names should be unique.
> Also, the fwnode name actually contains the reg property, so this name
> looks like "endpoint at 0-1" now... I'll change the name from fwnode name

This should be "endpoint at 0-0", or "endpoint at 1-1@. The `port_num` value
has the same number as the `reg` property

> to dev_name() per Dmitry's comment.
> > ...
> >
> > > +/**
> > > + * drm_dp_register_typec_switches() - register Type-C switches
> > > + * @dev: Device that registers Type-C switches
> > > + * @port: Device node for the switch
> > > + * @switch_desc: A Type-C switch descriptor
> > > + * @data: Private data for the switches
> > > + * @mux_set: Callback function for typec_mux_set
> > > + *
> > > + * This function registers USB Type-C switches for DP bridges that can switch
> > > + * the output signal between their output pins. This function uses devm_kcalloc
> > > + * to allocate memory, so it is expected to only call this in the driver probe
> > > + * functions.
> > > + *
> > > + * Currently only mode switches are implemented, and the function assumes the
> > > + * given @port device node has endpoints with "mode-switch" property.
> > > + * The port number is determined by the "reg" property of the endpoint.
> >
> > `kernel-doc -v ...` should complain on absence of "Return" section.
> >
> > > + */
> >
> > ...
> >
> > > +     switch_desc->typec_ports = devm_kcalloc(dev, switch_desc->num_typec_switches,
> > > +                                             sizeof(struct drm_dp_typec_port_data),
> >
> >                                                 sizeof(*switch_desc_typec_ports),
> >
> > ?
> >
> > > +                                             GFP_KERNEL);
> > > +     if (!switch_desc->typec_ports)
> > > +             return -ENOMEM;
> >
> > ...
> >
> > > +#ifdef CONFIG_DRM_DISPLAY_DP_TYPEC_HELPER
> >
> > Ah, maybe this should use IS_REACHABLE() ?
>
> CONFIG_DRM_DISPLAY_DP_TYPEC_HELPER is a boolean. Is there any
> difference between IS_REACHABLE and ifdef when the given config is a
> boolean?
> >
> > > +void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc);
> > > +int drm_dp_register_typec_switches(struct device *dev, struct fwnode_handle *port,
> > > +                                struct drm_dp_typec_switch_desc *switch_desc,
> > > +                                void *data, typec_mux_set_fn_t mux_set);
> > > +#else
> > > +static inline void drm_dp_unregister_typec_switches(struct drm_dp_typec_switch_desc *switch_desc)
> > > +{
> > > +}
> > > +static inline int drm_dp_register_typec_switches(
> > > +             struct device *dev, struct fwnode_handle *port,
> > > +             struct drm_dp_typec_switch_desc *switch_desc, void *data,
> > > +             typec_mux_set_fn_t mux_set)
> > > +{
> > > +     return -EOPNOTSUPP;
> > > +}
> > > +#endif
> >
> > --
> > With Best Regards,
> > Andy Shevchenko
> >
>
> Best regards,
> Pin-yen
> >