linux-kernel - RE: [PATCH] extcon: ptn5150: add usb role class support

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Date:   Tue, 19 Apr 2022 07:48:51 +0000
From:   Jun Li <jun.li@....com>
To:     Chanwoo Choi <cw00.choi@...sung.com>,
        "myungjoo.ham@...sung.com" <myungjoo.ham@...sung.com>,
        "krzk@...nel.org" <krzk@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Frank Li <frank.li@....com>, Xu Yang <xu.yang_2@....com>
Subject: RE: [PATCH] extcon: ptn5150: add usb role class support

Hi

> -----Original Message-----
> From: Chanwoo Choi <cw00.choi@...sung.com>
> Sent: Thursday, April 7, 2022 10:18 AM
> To: Jun Li <jun.li@....com>; myungjoo.ham@...sung.com; krzk@...nel.org
> Cc: linux-kernel@...r.kernel.org; Frank Li <frank.li@....com>; Xu Yang
> <xu.yang_2@....com>
> Subject: Re: [PATCH] extcon: ptn5150: add usb role class support
> 
> Hi,
> 
> On 4/6/22 6:42 PM, Li Jun wrote:
> > Add support of usb role class consumer to do role switch.
> >
> > Signed-off-by: Li Jun <jun.li@....com>
> > ---
> >  drivers/extcon/Kconfig          |  1 +
> >  drivers/extcon/extcon-ptn5150.c | 39
> > +++++++++++++++++++++++++++++++++
> >  2 files changed, 40 insertions(+)
> >
> > diff --git a/drivers/extcon/Kconfig b/drivers/extcon/Kconfig index
> > 0d42e49105dd..9828ade787a8 100644
> > --- a/drivers/extcon/Kconfig
> > +++ b/drivers/extcon/Kconfig
> > @@ -132,6 +132,7 @@ config EXTCON_PTN5150
> >  	tristate "NXP PTN5150 CC LOGIC USB EXTCON support"
> >  	depends on I2C && (GPIOLIB || COMPILE_TEST)
> >  	select REGMAP_I2C
> > +	select USB_ROLE_SWITCH
> >  	help
> >  	  Say Y here to enable support for USB peripheral and USB host
> >  	  detection by NXP PTN5150 CC (Configuration Channel) logic chip.
> > diff --git a/drivers/extcon/extcon-ptn5150.c
> > b/drivers/extcon/extcon-ptn5150.c index 5b9a3cf8df26..821b0f390308
> > 100644
> > --- a/drivers/extcon/extcon-ptn5150.c
> > +++ b/drivers/extcon/extcon-ptn5150.c
> > @@ -17,6 +17,7 @@
> >  #include <linux/slab.h>
> >  #include <linux/extcon-provider.h>
> >  #include <linux/gpio/consumer.h>
> > +#include <linux/usb/role.h>
> >
> >  /* PTN5150 registers */
> >  #define PTN5150_REG_DEVICE_ID			0x01
> > @@ -52,6 +53,7 @@ struct ptn5150_info {
> >  	int irq;
> >  	struct work_struct irq_work;
> >  	struct mutex mutex;
> > +	struct usb_role_switch *role_sw;
> >  };
> >
> >  /* List of detectable cables */
> > @@ -85,6 +87,12 @@ static void ptn5150_check_state(struct ptn5150_info
> *info)
> >  		extcon_set_state_sync(info->edev, EXTCON_USB_HOST, false);
> >  		gpiod_set_value_cansleep(info->vbus_gpiod, 0);
> >  		extcon_set_state_sync(info->edev, EXTCON_USB, true);
> > +
> > +		ret = usb_role_switch_set_role(info->role_sw, USB_ROLE_DEVICE);
> > +		if (ret)
> > +			dev_err(info->dev, "failed to set device role: %d\n",
> > +				ret);
> 
> > +
> >  		break;
> >  	case PTN5150_UFP_ATTACHED:
> >  		extcon_set_state_sync(info->edev, EXTCON_USB, false); @@ -95,6
> > +103,12 @@ static void ptn5150_check_state(struct ptn5150_info *info)
> >  			gpiod_set_value_cansleep(info->vbus_gpiod, 1);
> >
> >  		extcon_set_state_sync(info->edev, EXTCON_USB_HOST, true);
> > +
> > +		ret = usb_role_switch_set_role(info->role_sw, USB_ROLE_HOST);
> > +		if (ret)
> > +			dev_err(info->dev, "failed to set host role: %d\n",
> > +				ret);
> > +
> >  		break;
> >  	default:
> >  		break;
> > @@ -133,6 +147,13 @@ static void ptn5150_irq_work(struct work_struct
> *work)
> >  			extcon_set_state_sync(info->edev,
> >  					EXTCON_USB, false);
> >  			gpiod_set_value_cansleep(info->vbus_gpiod, 0);
> > +
> > +			ret = usb_role_switch_set_role(info->role_sw,
> > +						       USB_ROLE_NONE);
> > +			if (ret)
> > +				dev_err(info->dev,
> > +					"failed to set none role: %d\n",
> > +					ret);
> >  		}
> >  	}
> >
> > @@ -194,6 +215,14 @@ static int ptn5150_init_dev_type(struct ptn5150_info
> *info)
> >  	return 0;
> >  }
> >
> > +static void ptn5150_put_role_sw(void *data) {
> > +	struct ptn5150_info *info = data;
> > +
> > +	cancel_work_sync(&info->irq_work);
> > +	usb_role_switch_put(info->role_sw);
> > +}
> > +
> >  static int ptn5150_i2c_probe(struct i2c_client *i2c)  {
> >  	struct device *dev = &i2c->dev;
> > @@ -284,6 +313,16 @@ static int ptn5150_i2c_probe(struct i2c_client *i2c)
> >  	if (ret)
> >  		return -EINVAL;
> >
> > +	info->role_sw = usb_role_switch_get(info->dev);
> > +	if (IS_ERR(info->role_sw))
> > +		return PTR_ERR(info->role_sw);
> 
> If usb_role_switch is optional, you don't need to return error when
> usb_role_switch_get returns error. Because 'usb_role_switch_set_role'
> on this patch doesn't break the sequence. Just print the error log if error
> case.

Yes, it's optional, if the usb role switch is not provided, then
usb_role_switch_get() will return NULL, then usb role switch will
do nothing;
if the usb role switch is provided(intended to use) but there is
something wrong to get it, we must return error to force a failure
in probe(including probe defer).

Li Jun
> 
> > +
> > +	if (info->role_sw) {
> > +		ret = devm_add_action_or_reset(dev, ptn5150_put_role_sw, info);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> >  	/*
> >  	 * Update current extcon state if for example OTG connection was there
> >  	 * before the probe
> >
> 
> 
> --
> Best Regards,
> Chanwoo Choi
> Samsung Electronics