linux-kernel - Re: [PATCH 2/2] platform/chrome: typec: Register Type C switches

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Message-ID: <CACeCKadOzR++ctpG52ZBZZewXFRz39crHotsTC9+MjSWBoE_Dg@mail.gmail.com>
Date:   Wed, 29 Apr 2020 16:02:25 -0700
From:   Prashant Malani <pmalani@...omium.org>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Tim Wawrzynczak <twawrzynczak@...omium.org>,
        Benson Leung <bleung@...omium.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Guenter Roeck <groeck@...omium.org>,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH 2/2] platform/chrome: typec: Register Type C switches

Hi Enric,

Thanks for your review. Kindly see inline:

On Wed, Apr 29, 2020 at 3:22 PM Enric Balletbo i Serra
<enric.balletbo@...labora.com> wrote:
>
> Hi Prashant,
>
> Thank you for your patch.
>
> On 23/4/20 0:22, Prashant Malani wrote:
> > Register Type C mux and switch handles, when provided via firmware
> > bindings. These will allow the cros-ec-typec driver, and also alternate
> > mode drivers to configure connected Muxes correctly, according to PD
> > information retrieved from the Chrome OS EC.
> >
> > Signed-off-by: Prashant Malani <pmalani@...omium.org>
> > ---
> >  drivers/platform/chrome/cros_ec_typec.c | 47 +++++++++++++++++++++++++
> >  1 file changed, 47 insertions(+)
> >
> > diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
> > index eda57db26f8d..324ead297c4d 100644
> > --- a/drivers/platform/chrome/cros_ec_typec.c
> > +++ b/drivers/platform/chrome/cros_ec_typec.c
> > @@ -14,6 +14,8 @@
> >  #include <linux/platform_data/cros_usbpd_notify.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/usb/typec.h>
> > +#include <linux/usb/typec_mux.h>
> > +#include <linux/usb/role.h>
> >
> >  #define DRV_NAME "cros-ec-typec"
> >
> > @@ -25,6 +27,9 @@ struct cros_typec_port {
> >       struct typec_partner *partner;
> >       /* Port partner PD identity info. */
> >       struct usb_pd_identity p_identity;
> > +     struct typec_switch *ori_sw;
> > +     struct typec_mux *mux;
> > +     struct usb_role_switch *role_sw;
> >  };
> >
> >  /* Platform-specific data for the Chrome OS EC Type C controller. */
> > @@ -84,6 +89,40 @@ static int cros_typec_parse_port_props(struct typec_capability *cap,
> >       return 0;
> >  }
> >
> > +static int cros_typec_get_switch_handles(struct cros_typec_port *port,
> > +                                      struct fwnode_handle *fwnode,
> > +                                      struct device *dev)
> > +{
> > +     port->mux = fwnode_typec_mux_get(fwnode, NULL);
> > +     if (IS_ERR(port->mux)) {
>
> Should you return an error if NULL is returned (IS_ERR_OR_NULL) ? I think that
> fwnode_typec_mux_get can return NULL too.
I think returning NULL can be considered "not an error" for devices
that don't have kernel-controlled muxes (which won't have this
property defined).
So this check should be fine as is.
>
>
> > +             dev_info(dev, "Mux handle not found.\n");
> > +             goto mux_err;
> > +     }
> > +
> > +     port->ori_sw = fwnode_typec_switch_get(fwnode);
> > +     if (IS_ERR(port->ori_sw)) {
>
> ditto
>
> > +             dev_info(dev, "Orientation switch handle not found.\n");
> > +             goto ori_sw_err;
> > +     }
> > +
> > +     port->role_sw = fwnode_usb_role_switch_get(fwnode);
> > +     if (IS_ERR(port->role_sw)) {
>
> ditto
>
> > +             dev_info(dev, "USB role switch handle not found.\n");
> > +             goto role_sw_err;
> > +     }
> > +
> > +     return 0;
> > +
> > +role_sw_err:
> > +     usb_role_switch_put(port->role_sw);
> > +ori_sw_err:
> > +     typec_switch_put(port->ori_sw);
> > +mux_err:
> > +     typec_mux_put(port->mux);
> > +
> > +     return -ENODEV;
> > +}
> > +
> >  static void cros_unregister_ports(struct cros_typec_data *typec)
> >  {
> >       int i;
> > @@ -91,6 +130,9 @@ static void cros_unregister_ports(struct cros_typec_data *typec)
> >       for (i = 0; i < typec->num_ports; i++) {
> >               if (!typec->ports[i])
> >                       continue;
> > +             usb_role_switch_put(typec->ports[i]->role_sw);
> > +             typec_switch_put(typec->ports[i]->ori_sw);
> > +             typec_mux_put(typec->ports[i]->mux);
> >               typec_unregister_port(typec->ports[i]->port);
> >       }
> >  }
> > @@ -153,6 +195,11 @@ static int cros_typec_init_ports(struct cros_typec_data *typec)
> >                       ret = PTR_ERR(cros_port->port);
> >                       goto unregister_ports;
> >               }
> > +
> > +             ret = cros_typec_get_switch_handles(cros_port, fwnode, dev);
> > +             if (ret)
> > +                     dev_info(dev, "No switch control for port %d\n",
> > +                              port_num);
>
> When drivers are working, they should not spit out any messages, make
> this dev_dbg() at the most. Be quiet, please.
Ack. Will update this in the next version.
>
>
> >       }
> >
> >       return 0;
> >