Re: [RESEND PATCH] usb: common: usb-conn-gpio: Register optional charger

[Paul Cercueil]

Le dim. 26 juil. 2020 à 10:39, Greg Kroah-Hartman 
<gregkh@xxxxxxxxxxxxxxxxxxx> a écrit :
> On Sat, Jul 25, 2020 at 07:51:14PM +0200, Paul Cercueil wrote:
> >  Hi Greg,
> >
> >  Le mar. 21 juil. 2020 à 13:41, Greg Kroah-Hartman
> >  <gregkh@xxxxxxxxxxxxxxxxxxx> a écrit :
> >  > On Mon, Jun 22, 2020 at 12:48:07AM +0200, Paul Cercueil wrote:
> >  > >  Register a power supply charger, if the Kconfig option
> >  > >  USB_CONN_GPIO_CHARGER is set, whose online state depends on 
> > whether
> >  > >  the USB role is set to device or not.
> >  > >
> >  > >  This is useful when the USB role is the only way to know if the
> >  > > device
> >  > >  is charging from USB. The API is the standard power supply 
> > charger
> >  > > API,
> >  > >  you get a /sys/class/power_supply/xxx/online node which tells 
> > you
> >  > > the
> >  > >  state of the charger.
> >  > >
> >  > >  The sole purpose of this is to give userspace applications a 
> > way to
> >  > >  know whether or not the charger is plugged.
> >  > >
> >  > >  Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> >  > >  ---
> >  > >   drivers/usb/common/Kconfig         | 11 +++++++
> >  > >   drivers/usb/common/usb-conn-gpio.c | 47
> >  > > ++++++++++++++++++++++++++++++
> >  > >   2 files changed, 58 insertions(+)
> >  > >
> >  > >  diff --git a/drivers/usb/common/Kconfig 
> > b/drivers/usb/common/Kconfig
> >  > >  index d611477aae41..5405ae96c68f 100644
> >  > >  --- a/drivers/usb/common/Kconfig
> >  > >  +++ b/drivers/usb/common/Kconfig
> >  > >  @@ -49,3 +49,14 @@ config USB_CONN_GPIO
> >  > >
> >  > >   	  To compile the driver as a module, choose M here: the 
> > module
> >  > > will
> >  > >   	  be called usb-conn-gpio.ko
> >  > >  +
> >  > >  +if USB_CONN_GPIO
> >  > >  +
> >  > >  +config USB_CONN_GPIO_CHARGER
> >  > >  +	bool "USB charger support"
> >  > >  +	select POWER_SUPPLY
> >  > >  +	help
> >  > >  +	  Register a charger with the power supply subsystem. This 
> > will
> >  > > allow
> >  > >  +	  userspace to know whether or not the device is charging 
> > from
> >  > > USB.
> >  >
> >  > Why make this an option at all?  Why wouldn't we always want this 
> > here?
> >  >
> >  > As this is a charger, exporting that information to userspace 
> > should
> >  > probably always happen, right?
> >
> >  I wanted to avoid the hardcoded dependency on CONFIG_POWER_SUPPLY.
> >
> >  I can very well make that non-optional.
>
> As the whole reason for this driver is to be a power supply, make it
> depend on the power supply core please.

It's the whole reason of my patch, not of the driver itself, whose 
purpose is to report the USB role (device, host, unconnected).

-Paul