Date:   Fri, 31 Mar 2023 11:36:40 +0900
From:   Pin-yen Lin <treapking@...omium.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Robert Foss <rfoss@...nel.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
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        Daniel Vetter <daniel@...ll.ch>,
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        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
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        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
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        Prashant Malani <pmalani@...omium.org>,
        Benson Leung <bleung@...omium.org>,
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        Xin Ji <xji@...logixsemi.com>, linux-kernel@...r.kernel.org,
        Thomas Zimmermann <tzimmermann@...e.de>,
        linux-acpi@...r.kernel.org,
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        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Lyude Paul <lyude@...hat.com>,
        Nícolas F . R . A . Prado 
        <nfraprado@...labora.com>, Allen Chen <allen.chen@....com.tw>,
        dri-devel@...ts.freedesktop.org, Marek Vasut <marex@...x.de>,
        Stephen Boyd <swboyd@...omium.org>,
        chrome-platform@...ts.linux.dev, devicetree@...r.kernel.org,
        Andi Shyti <andi.shyti@...ux.intel.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Douglas Anderson <dianders@...omium.org>,
        Imre Deak <imre.deak@...el.com>,
        Jani Nikula <jani.nikula@...el.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        YueHaibing <yuehaibing@...wei.com>
Subject: Re: [PATCH v14 03/10] drm/display: Add Type-C switch helpers

Hi Andy,

Thanks for the review.

On Wed, Mar 22, 2023 at 8:01 PM Andy Shevchenko
<andriy.shevchenko@...ux.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@0-1" now... I'll change the name from fwnode name
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
>

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