Re: [PATCH 08/18] staging: typec: fusb302: Add support for USB2 charger detection through extcon

[Guenter Roeck]

On 08/06/2017 07:36 AM, Hans de Goede wrote:
> Hi,
>
> On 06-08-17 16:22, Guenter Roeck wrote:
> > On 08/06/2017 05:35 AM, Hans de Goede wrote:
> > > The fusb302 port-controller relies on an external device doing USB2
> > > charger-type detection.
> > >
> > > The Intel Whiskey Cove PMIC with which the fusb302 is combined on some
> > > X86/ACPI platforms already has a charger-type detection driver which
> > > uses extcon to communicate the detected charger-type.
> > >
> > > This commit uses the tcpm_get_usb2_current_limit_extcon helper to enable
> > > USB2 charger detection on these systems. Note that the "fcs,extcon-name"
> > > property name is only for kernel internal use by X86/ACPI platform code
> > > and as such is NOT documented in the devicetree bindings.
> > >
> > > Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> > > ---
> > >   drivers/staging/typec/fusb302/fusb302.c | 16 ++++++++++++++++
> > >   1 file changed, 16 insertions(+)
> > >
> > > diff --git a/drivers/staging/typec/fusb302/fusb302.c b/drivers/staging/typec/fusb302/fusb302.c
> > > index be454b5ff6c7..1d8c9b66df2f 100644
> > > --- a/drivers/staging/typec/fusb302/fusb302.c
> > > +++ b/drivers/staging/typec/fusb302/fusb302.c
> > > @@ -1201,6 +1201,8 @@ static void init_tcpc_dev(struct tcpc_dev *fusb302_tcpc_dev)
> > >   {
> > >       fusb302_tcpc_dev->init = tcpm_init;
> > >       fusb302_tcpc_dev->get_vbus = tcpm_get_vbus;
> > > +    fusb302_tcpc_dev->get_usb2_current_limit =
> > > +        tcpm_get_usb2_current_limit_extcon;
> > >       fusb302_tcpc_dev->set_cc = tcpm_set_cc;
> > >       fusb302_tcpc_dev->get_cc = tcpm_get_cc;
> > >       fusb302_tcpc_dev->set_polarity = tcpm_set_polarity;
> > > @@ -1685,6 +1687,7 @@ static int fusb302_probe(struct i2c_client *client,
> > >       struct fusb302_chip *chip;
> > >       struct i2c_adapter *adapter;
> > >       struct device *dev = &client->dev;
> > > +    const char *name;
> > >       int ret = 0;
> > >       u32 val;
> > > @@ -1717,6 +1720,19 @@ static int fusb302_probe(struct i2c_client *client,
> > >       if (device_property_read_u32(dev, "fcs,operating-snk-mw", &val) == 0)
> > >           chip->tcpc_config.operating_snk_mw = val;
> > > +    /*
> > > +     * Devicetree platforms should get extcon via phandle (not yet
> > > +     * supported). On ACPI platforms, we get the name from a device prop.
> > > +     * This device prop is for kernel internal use only and is expected
> > > +     * to be set by the platform code which also registers the i2c client
> > > +     * for the fusb302.
> > > +     */
> > > +    if (device_property_read_string(dev, "fcs,extcon-name", &name) == 0) {
> >
> > Those new devicetree properties need to be documented and approved by dt maintainers.
>
> As indicated by the comment, this property should not be used in the devicetree
> case, notice this is a device-property and not an of property and since it is
> not intended to be used with devicetree at all (in devicetree a phandle rather
> then a name would be used), it has no place under Documentation/devicetree at all.

Ok. I thought device properties were supposed to unify dt and non-dt situations,
but apparently not. Oh well :-(.

> Also there is no current binding documentation for the "fcs,fusb302" compatible
> and the weird "fcs,int_n" gpio which really is an irq which it already uses.

Yes, one of those TODO items for moving the code out of staging. "fcs," should
possibly be "fusb302,", and int_n _is_ weird.

> > > +        chip->tcpc_dev.usb2_extcon = extcon_get_extcon_dev(name);
> > > +        if (!chip->tcpc_dev.usb2_extcon)
> >
> > extcon_get_extcon_dev() can also return an ERR_PTR.
> >
> > As before, I am not really happy typing this into tcpm via tcpc_dev.
> > Until we have a better solution, I would prefer for that code to stay with the fusb302
> > code.
>
> Ok, I tried to make this all re-usable since I think other port-controller drivers
> will need something similar, but I can kill the entire tcpm-helpers.c file in v2
> and then put everything in fusb302.c. I take it that that is what you want ?
Yes, please.

Also, please copy Yueyao Zhu for the fusb302 changes in v2.

Thanks,
Guenter