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

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Message-ID: <3a4a88a9-f0e3-2b65-9df4-6c1d4e3f1c14@roeck-us.net>
Date:   Sun, 17 Jan 2021 09:43:48 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     cy_huang <u0084500@...il.com>, heikki.krogerus@...ux.intel.com,
        matthias.bgg@...il.com, robh+dt@...nel.org
Cc:     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 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.
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");
>