Re: [PATCH 1/2] usb typec: tcpci: mt6360: Add vsafe0v support and external vbus supply control

[ChiYuan Huang]

Guenter Roeck <linux@xxxxxxxxxxxx> 於 2021年1月18日 週一 上午1:43寫道：
>
> On 1/15/21 6:13 AM, cy_huang wrote:
> > From: ChiYuan Huang <cy_huang@xxxxxxxxxxx>
> >
> > MT6360 not support for TCPC command to control source and sink.
>
> does not
>
Ack
> > Uses external 5V vbus regulator as the vbus source control.
> >
> Use
>
Ack
> > Also adds the capability to report vsafe0v.
> >
> add
>
Ack
> So far this driver works without regulator. Unless I am missing something,
> this patch makes regulator support mandatory, meaning existing code will fail.
> I am not sure if that is appropriate/acceptable. Can we be sure that this will
> work for existing users of this driver ?
>
Yes, I already checked all the src/snk functionality based on  the
latest typec code.
It'll be common for our TCPC. It didn't support for TCPC command.
>From the recent patches, actually, I have the local change to test the
src capability.
But I didn't submit it. It's almost the same to add set_vbus callback.
That's why I submit this change after tcpci 'set_vbus callback' is added.

> Thanks,
> Guenter
>
> > Signed-off-by: ChiYuan Huang <cy_huang@xxxxxxxxxxx>
> > ---
> >  drivers/usb/typec/tcpm/tcpci_mt6360.c | 29 +++++++++++++++++++++++++++++
> >  1 file changed, 29 insertions(+)
> >
> > diff --git a/drivers/usb/typec/tcpm/tcpci_mt6360.c b/drivers/usb/typec/tcpm/tcpci_mt6360.c
> > index f1bd9e0..0edf4b6 100644
> > --- a/drivers/usb/typec/tcpm/tcpci_mt6360.c
> > +++ b/drivers/usb/typec/tcpm/tcpci_mt6360.c
> > @@ -11,6 +11,7 @@
> >  #include <linux/of.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/regmap.h>
> > +#include <linux/regulator/consumer.h>
> >  #include <linux/usb/tcpm.h>
> >
> >  #include "tcpci.h"
> > @@ -36,6 +37,7 @@ struct mt6360_tcpc_info {
> >       struct tcpci_data tdata;
> >       struct tcpci *tcpci;
> >       struct device *dev;
> > +     struct regulator *vbus;
> >       int irq;
> >  };
> >
> > @@ -51,6 +53,27 @@ static inline int mt6360_tcpc_write16(struct regmap *regmap,
> >       return regmap_raw_write(regmap, reg, &val, sizeof(u16));
> >  }
> >
> > +static int mt6360_tcpc_set_vbus(struct tcpci *tcpci, struct tcpci_data *data, bool src, bool snk)
> > +{
> > +     struct mt6360_tcpc_info *mti = container_of(data, struct mt6360_tcpc_info, tdata);
> > +     int ret;
> > +
> > +     /* To correctly handle the already enabled vbus and disable its supply first */
> > +     if (regulator_is_enabled(mti->vbus)) {
> > +             ret = regulator_disable(mti->vbus);
> > +             if (ret)
> > +                     return ret;
> > +     }
>
> Is it really a good idea to disable vbus if it happens to be already enabled
> and there is (another ?) request to enable it ?
>
Yes, for  the state change from src_attach_wait to src_attach,
It need to meet the requirement that  the vbus is at vsafe0v.
So to disable it first is needed.
And to prevent other users from enabling/disabling external vbus
regulator in any case.
I think we may change regulator_get  to 'regulator_get_exclusive'.
>From the design, 5v regulator only can be controlled via typec framework.
If other user touch it, it'll affect the typec state transition.
> > +
> > +     if (src) {
> > +             ret = regulator_enable(mti->vbus);
> > +             if (ret)
> > +                     return ret;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> >  static int mt6360_tcpc_init(struct tcpci *tcpci, struct tcpci_data *tdata)
> >  {
> >       struct regmap *regmap = tdata->regmap;
> > @@ -138,7 +161,13 @@ static int mt6360_tcpc_probe(struct platform_device *pdev)
> >       if (mti->irq < 0)
> >               return mti->irq;
> >
> > +     mti->vbus = devm_regulator_get(&pdev->dev, "vbus");
> > +     if (IS_ERR(mti->vbus))
> > +             return PTR_ERR(mti->vbus);
> > +
> >       mti->tdata.init = mt6360_tcpc_init;
> > +     mti->tdata.set_vbus = mt6360_tcpc_set_vbus;
> > +     mti->tdata.vbus_vsafe0v = 1;
> >       mti->tcpci = tcpci_register_port(&pdev->dev, &mti->tdata);
> >       if (IS_ERR(mti->tcpci)) {
> >               dev_err(&pdev->dev, "Failed to register tcpci port\n");
> >
>