linux-kernel - Re: [PATCH v2] platform/chrome: cros_ec_typec: allow deferred probe of switch handles

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Date:   Tue, 24 Jan 2023 18:46:13 +1100
From:   Victor Ding <victording@...omium.org>
To:     Guenter Roeck <groeck@...gle.com>
Cc:     linux-kernel@...r.kernel.org, chrome-platform@...ts.linux.dev,
        dustin@...ett.net, lee.jones@...aro.org, bleung@...omium.org,
        dnojiri@...omium.org, sebastian.reichel@...labora.com,
        gregkh@...uxfoundation.org, pmalani@...omium.org,
        gustavoars@...nel.org, groeck@...omium.org,
        enric.balletbo@...labora.com, tinghan.shen@...iatek.com,
        heikki.krogerus@...ux.intel.com, tzungbi@...nel.org
Subject: Re: [PATCH v2] platform/chrome: cros_ec_typec: allow deferred probe
 of switch handles

On Tue, Jan 24, 2023 at 5:57 PM Guenter Roeck <groeck@...gle.com> wrote:
>
> On Mon, Jan 23, 2023 at 10:16 PM Victor Ding <victording@...omium.org> wrote:
> >
> > `fwnode_typec_{retimer,mux,switch}_get()` could return `-EPROBE_DEFER`,
> > which is called from `cros_typec_get_switch_handles`. When this happens,
> > it does not indicate absence of switches; instead, it only hints that
> > probing of switches should occur at a later time.
> >
> > Progagate `-EPROBE_DEFER` to upper layer logic so that they can re-try
> > probing switches as a better time.
> >
> > Signed-off-by: Victor Ding <victording@...omium.org>
> > ---
> >
> > Changes in v2:
> > - Coverted switch-block to nested if-blocks.
> >
> >  drivers/platform/chrome/cros_ec_typec.c | 26 ++++++++++++++++---------
> >  1 file changed, 17 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/platform/chrome/cros_ec_typec.c b/drivers/platform/chrome/cros_ec_typec.c
> > index 59de4ce01fab..580f3bdf091c 100644
> > --- a/drivers/platform/chrome/cros_ec_typec.c
> > +++ b/drivers/platform/chrome/cros_ec_typec.c
> > @@ -145,31 +145,37 @@ static int cros_typec_get_switch_handles(struct cros_typec_port *port,
> >                                          struct fwnode_handle *fwnode,
> >                                          struct device *dev)
> >  {
> > +       int ret = 0;
> > +
> >         port->mux = fwnode_typec_mux_get(fwnode, NULL);
> >         if (IS_ERR(port->mux)) {
> > -               dev_dbg(dev, "Mux handle not found.\n");
> > +               ret = PTR_ERR(port->mux);
> > +               dev_dbg(dev, "Mux handle not found: %d.\n", ret);
> >                 goto mux_err;
> >         }
> >
> >         port->retimer = fwnode_typec_retimer_get(fwnode);
> >         if (IS_ERR(port->retimer)) {
> > -               dev_dbg(dev, "Retimer handle not found.\n");
> > +               ret = PTR_ERR(port->retimer);
> > +               dev_dbg(dev, "Retimer handle not found: %d.\n", ret);
> >                 goto retimer_sw_err;
> >         }
> >
> >         port->ori_sw = fwnode_typec_switch_get(fwnode);
> >         if (IS_ERR(port->ori_sw)) {
> > -               dev_dbg(dev, "Orientation switch handle not found.\n");
> > +               ret = PTR_ERR(port->ori_sw);
> > +               dev_dbg(dev, "Orientation switch handle not found: %d\n", ret);
> >                 goto ori_sw_err;
> >         }
> >
> >         port->role_sw = fwnode_usb_role_switch_get(fwnode);
> >         if (IS_ERR(port->role_sw)) {
> > -               dev_dbg(dev, "USB role switch handle not found.\n");
> > +               ret = PTR_ERR(port->role_sw);
> > +               dev_dbg(dev, "USB role switch handle not found: %d\n", ret);
> >                 goto role_sw_err;
> >         }
> >
> > -       return 0;
> > +       return ret;
> >
>
> This change is pointless.
Sure, I'll revert this line to `return 0` in the next revision.
>
> Guenter
>
> >  role_sw_err:
> >         typec_switch_put(port->ori_sw);
> > @@ -181,7 +187,7 @@ static int cros_typec_get_switch_handles(struct cros_typec_port *port,
> >         typec_mux_put(port->mux);
> >         port->mux = NULL;
> >  mux_err:
> > -       return -ENODEV;
> > +       return ret;
> >  }
> >
> >  static int cros_typec_add_partner(struct cros_typec_data *typec, int port_num,
> > @@ -423,9 +429,11 @@ static int cros_typec_init_ports(struct cros_typec_data *typec)
> >                 }
> >
> >                 ret = cros_typec_get_switch_handles(cros_port, fwnode, dev);
> > -               if (ret)
> > -                       dev_dbg(dev, "No switch control for port %d\n",
> > -                               port_num);
> > +               if (ret) {
> > +                       dev_dbg(dev, "No switch control for port %d, err: %d\n", port_num, ret);
> > +                       if (ret == -EPROBE_DEFER)
> > +                               goto unregister_ports;
> > +               }
> >
> >                 ret = cros_typec_register_port_altmodes(typec, port_num);
> >                 if (ret) {
> > --
> > 2.39.1.405.gd4c25cc71f-goog
> >