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

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Message-ID: <AM5PR1001MB0994B54049DDCF2CE376263A80670@AM5PR1001MB0994.EURPRD10.PROD.OUTLOOK.COM>
Date:   Thu, 14 Feb 2019 14:17:14 +0000
From:   Adam Thomson <Adam.Thomson.Opensource@...semi.com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Greg KH <gregkh@...uxfoundation.org>,
        Kyle Tso <kyletso@...gle.com>
CC:     Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Badhri Jagan Sridharan <badhri@...gle.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] usb: typec: tcpm: Export partner Source Capabilities

On 12 February 2019 16:20, Guenter Roeck wrote:

> On 2/12/19 2:54 AM, Greg KH wrote:
> > 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?
> >
> 
> Agreed - that code should be sent upstream as well to let us see the entire
> context.
> 
> >> 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...
> >
> 
> I sent a patch to do just that. Quite frankly I don't recal why I thought those
> functions might be needed.

As a mind jog - https://lkml.org/lkml/2017/11/27/1256 :)