Date:   Tue, 19 Jan 2021 16:23:56 +0800
From:   ChiYuan Huang <u0084500@...il.com>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>
Cc:     Guenter Roeck <linux@...ck-us.net>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        matthias.bgg@...il.com, Rob Herring <robh+dt@...nel.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Linux USB List <linux-usb@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        lkml <linux-kernel@...r.kernel.org>,
        cy_huang <cy_huang@...htek.com>, gene_chen@...htek.com,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH 1/2] usb typec: tcpci: mt6360: Add vsafe0v support and
 external vbus supply control

Chunfeng Yun <chunfeng.yun@...iatek.com> 於 2021年1月19日 週二 下午3:38寫道：
>
> On Mon, 2021-01-18 at 16:28 +0800, ChiYuan Huang wrote:
> > Guenter Roeck <linux@...ck-us.net> 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@...htek.com>
> > > >
> > > > 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@...htek.com>
> > > > ---
> > > >  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.
> How about to process the case that even switch usb controller to device
> mode, platform also need to keep vbus on? e.g. Iphone Carplay
>
>
It must be processed by USBPD data role swap.

Type C only decide the initial role (SNK: power snk and ufp; SRC:
power src and DFP).
Only USBPD can change the power/data/vconn role individually.

> > > > +
> > > > +     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");
> > > >
> > >
>

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