linux-kernel - Re: [PATCH v1 3/3] usb: typec: ucsi: Get PD revision for partner

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Date: Wed, 24 Jan 2024 11:18:37 -0800
From: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
To: Prashant Malani <pmalani@...omium.org>
Cc: Abhishek Pandit-Subedi <abhishekpandit@...gle.com>, 
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>, linux-usb@...r.kernel.org, 
	jthies@...gle.com, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
	Bjorn Andersson <andersson@...nel.org>, Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, 
	Fabrice Gasnier <fabrice.gasnier@...s.st.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Hans de Goede <hdegoede@...hat.com>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Saranya Gopal <saranya.gopal@...el.com>, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 3/3] usb: typec: ucsi: Get PD revision for partner

On Wed, Jan 24, 2024 at 10:49 AM Prashant Malani <pmalani@...omium.org> wrote:
>
> Hi Abhishek,
>
> On Tue, Jan 23, 2024 at 2:30 PM Abhishek Pandit-Subedi
> <abhishekpandit@...gle.com> wrote:
> >
> > From: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
> >
> > PD major revision for the port partner is described in
> > GET_CONNECTOR_CAPABILITY and is only valid on UCSI 2.0 and newer. Update
> > the pd_revision on the partner if the UCSI version is 2.0 or newer.
> >
> > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@...omium.org>
> > ---
> > $ cat /sys/class/typec/port2-partner/usb_power_delivery_revision
> > 3.0
> >
> >  drivers/usb/typec/ucsi/ucsi.c | 25 +++++++++++++++++++++++++
> >  drivers/usb/typec/ucsi/ucsi.h |  3 +++
> >  2 files changed, 28 insertions(+)
> >
> > diff --git a/drivers/usb/typec/ucsi/ucsi.c b/drivers/usb/typec/ucsi/ucsi.c
> > index 4edf785d203b..8e0a512853ba 100644
> > --- a/drivers/usb/typec/ucsi/ucsi.c
> > +++ b/drivers/usb/typec/ucsi/ucsi.c
> > @@ -782,6 +782,8 @@ static int ucsi_register_partner(struct ucsi_connector *con)
> >         }
> >
> >         desc.usb_pd = pwr_opmode == UCSI_CONSTAT_PWR_OPMODE_PD;
> > +       desc.pd_revision =
> > +               UCSI_CONCAP_FLAG_PARTNER_PD_MAJOR_REV_AS_BCD(con->cap.flags);
> >
> >         partner = typec_register_partner(con->port, &desc);
> >         if (IS_ERR(partner)) {
> > @@ -856,6 +858,28 @@ static void ucsi_partner_change(struct ucsi_connector *con)
> >                         con->num, u_role);
> >  }
> >
> > +static int ucsi_check_connector_capability(struct ucsi_connector *con)
> > +{
> > +       u64 command;
> > +       int ret;
> > +
> > +       if (!con->partner && !IS_MIN_VERSION_2_0(con->ucsi))
>
> (Mentioned side-band but reproducing here for consistency)
> This macro is unnecessary. It's just doing a comparison, which can be inlined
> without any perceptible change in readability (actually, I'd argue adding the !
> to an english idiom makes things *less* readable):

I prefer the macro because it makes it easier to search where version
checks are being done and it keeps the `<` vs `<=` consistent. UCSI
only has a few published revisions: 1.2, 2.0, 2.1 and 3.0 and major
changes seem to have happened in 2.0 and 3.0 so there should be very
few of these macros created/used.

>
>         if (!con->partner && con->ucsi->version < UCSI_VERSION_2_0)
>                return 0;
>
> Besides that, I think you want an || operator instead of the && operator, right?

Good catch on that. It should be OR.
i.e. if (!con->partner || !IS_MIN_VERSION_2_0(con->ucsi))

>
> > +               return 0;
> > +
> > +       command = UCSI_GET_CONNECTOR_CAPABILITY | UCSI_CONNECTOR_NUMBER(con->num);
> > +       ret = ucsi_send_command(con->ucsi, command, &con->cap, sizeof(con->cap));
> > +       if (ret < 0) {
> > +               dev_err(con->ucsi->dev, "GET_CONNECTOR_CAPABILITY failed (%d)\n", ret);
> > +               return ret;
> > +       }
> > +
> > +       typec_partner_set_pd_revision(
> > +               con->partner,
> > +               UCSI_CONCAP_FLAG_PARTNER_PD_MAJOR_REV_AS_BCD(con->cap.flags));
> > +
> > +       return ret;
> > +}
> > +
> >  static int ucsi_check_connection(struct ucsi_connector *con)
> >  {
> >         u8 prev_flags = con->status.flags;
>
> Thanks,