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

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Message-ID: <1611041612.12761.9.camel@mhfsdcap03>
Date:   Tue, 19 Jan 2021 15:33:32 +0800
From:   Chunfeng Yun <chunfeng.yun@...iatek.com>
To:     Guenter Roeck <linux@...ck-us.net>
CC:     cy_huang <u0084500@...il.com>, <heikki.krogerus@...ux.intel.com>,
        <matthias.bgg@...il.com>, <robh+dt@...nel.org>,
        <gregkh@...uxfoundation.org>, <linux-usb@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <cy_huang@...htek.com>,
        <gene_chen@...htek.com>, <devicetree@...r.kernel.org>
Subject: Re: [PATCH 1/2] usb typec: tcpci: mt6360: Add vsafe0v support and
 external vbus supply control

On Sun, 2021-01-17 at 09:43 -0800, Guenter Roeck wrote:
> 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
> 
> > Uses external 5V vbus regulator as the vbus source control.
> > 
> Use
> 
> > Also adds the capability to report vsafe0v.
> > 
> add
> 
> So far this driver works without regulator. Unless I am missing something,
> this patch makes regulator support mandatory, meaning existing code will fail.
If don't provide vbus-supply in DTS, regulator framework will provide a
dummy regulator, so the code will not fail.
> I am not sure if that is appropriate/acceptable. Can we be sure that this will
> work for existing users of this driver ?

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