linux-kernel - Re: [PATCH] usb: typec: tcpm: Export partner Source Capabilities

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Message-ID: <20190212105421.GA23271@kroah.com>
Date:   Tue, 12 Feb 2019 11:54:21 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Kyle Tso <kyletso@...gle.com>
Cc:     Guenter Roeck <linux@...ck-us.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Badhri Jagan Sridharan <badhri@...gle.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: typec: tcpm: Export partner Source Capabilities

On Tue, Feb 12, 2019 at 06:29:39PM +0800, Kyle Tso wrote:
> On Thu, Jan 31, 2019 at 3:02 PM Greg KH <gregkh@...uxfoundation.org> wrote:
> 
> > On Thu, Jan 31, 2019 at 11:54:11AM +0800, Kyle Tso wrote:
> > > Provide a function to get the partner Source Capabilities.
> > >
> > > Signed-off-by: Kyle Tso <kyletso@...gle.com>
> > > ---
> > >  drivers/usb/typec/tcpm/tcpm.c | 23 +++++++++++++++++++++++
> > >  include/linux/usb/tcpm.h      |  1 +
> > >  2 files changed, 24 insertions(+)
> > >
> > > diff --git a/drivers/usb/typec/tcpm/tcpm.c
> > b/drivers/usb/typec/tcpm/tcpm.c
> > > index f1d3e54210df..29cd84ba9960 100644
> > > --- a/drivers/usb/typec/tcpm/tcpm.c
> > > +++ b/drivers/usb/typec/tcpm/tcpm.c
> > > @@ -4494,6 +4494,29 @@ int tcpm_update_sink_capabilities(struct
> > tcpm_port *port, const u32 *pdo,
> > >  }
> > >  EXPORT_SYMBOL_GPL(tcpm_update_sink_capabilities);
> > >
> > > +/*
> > > + * Don't call this function in interrupt context. Caller needs to free
> > the
> > > + * memory itself.
> > > + */
> > > +int tcpm_get_partner_src_caps(struct tcpm_port *port, u32 **src_pdo)
> > > +{
> > > +     unsigned int nr_pdo;
> > > +
> > > +     if (port->nr_source_caps == 0)
> > > +             return -ENODATA;
> > > +
> > > +     *src_pdo = kcalloc(port->nr_source_caps, sizeof(u32), GFP_KERNEL);
> > > +     if (!src_pdo)
> > > +             return -ENOMEM;
> > > +
> > > +     mutex_lock(&port->lock);
> > > +     nr_pdo = tcpm_copy_pdos(*src_pdo, port->source_caps,
> > > +                             port->nr_source_caps);
> > > +     mutex_unlock(&port->lock);
> > > +     return nr_pdo;
> > > +}
> > > +EXPORT_SYMBOL_GPL(tcpm_get_partner_src_caps);
> >
> > We don't add new functions that no one uses :(
> >
> >
> This function is useful if the PD Device Policy Manager is implemented
> outside of TCPM.
> In this situation, Device Policy Manager needs to know the partner
> capabilities to optimize
> the charging process.

And where is that code?

> Take existing functions in TCPM for example:
> Function "tcpm_update_sink_capabilities" and
> "tcpm_update_source_capabilities" are exposed
> as well. And no one uses them now.

Great, let's go delete them now, we should not have apis that no one
uses.  This isn't a new thing...

thanks,

greg k-h