linux-kernel - Re: [PATCH 2/3] usb: common: add helper to get role-switch-default-mode

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Message-ID: <1622167640.5918.4.camel@mhfsdcap03>
Date:   Fri, 28 May 2021 10:07:20 +0800
From:   Chunfeng Yun <chunfeng.yun@...iatek.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     Felipe Balbi <balbi@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH 2/3] usb: common: add helper to get
 role-switch-default-mode

On Thu, 2021-05-27 at 12:01 +0200, Greg Kroah-Hartman wrote:
> On Thu, May 27, 2021 at 05:43:39PM +0800, Chunfeng Yun wrote:
> > On Thu, 2021-05-27 at 09:28 +0200, Greg Kroah-Hartman wrote:
> > > On Tue, May 25, 2021 at 04:59:24PM +0800, Chunfeng Yun wrote:
> > > > Add helper to get "role-switch-default-mode", and convert it
> > > > to the corresponding enum usb_dr_mode
> > > > 
> > > > Signed-off-by: Chunfeng Yun <chunfeng.yun@...iatek.com>
> > > > ---
> > > >  drivers/usb/common/common.c | 20 ++++++++++++++++++++
> > > >  include/linux/usb/otg.h     |  1 +
> > > >  2 files changed, 21 insertions(+)
> > > > 
> > > > diff --git a/drivers/usb/common/common.c b/drivers/usb/common/common.c
> > > > index fff318597337..78a625a4e526 100644
> > > > --- a/drivers/usb/common/common.c
> > > > +++ b/drivers/usb/common/common.c
> > > > @@ -207,6 +207,26 @@ enum usb_dr_mode usb_get_dr_mode(struct device *dev)
> > > >  }
> > > >  EXPORT_SYMBOL_GPL(usb_get_dr_mode);
> > > >  
> > > > +/**
> > > > + * usb_get_role_switch_default_mode - Get default mode for given device
> > > > + * @dev: Pointer to the given device
> > > > + *
> > > > + * The function gets string from property 'role-switch-default-mode',
> > > > + * and returns the corresponding enum usb_dr_mode.
> > > > + */
> > > > +enum usb_dr_mode usb_get_role_switch_default_mode(struct device *dev)
> > > > +{
> > > > +	const char *str;
> > > > +	int ret;
> > > > +
> > > > +	ret = device_property_read_string(dev, "role-switch-default-mode", &str);
> > > > +	if (ret < 0)
> > > > +		return USB_DR_MODE_UNKNOWN;
> > > > +
> > > > +	return usb_get_dr_mode_from_string(str);
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(usb_get_role_switch_default_mode);
> > > > +
> > > >  /**
> > > >   * usb_decode_interval - Decode bInterval into the time expressed in 1us unit
> > > >   * @epd: The descriptor of the endpoint
> > > > diff --git a/include/linux/usb/otg.h b/include/linux/usb/otg.h
> > > > index a86ee6aad51b..bde313c97fb6 100644
> > > > --- a/include/linux/usb/otg.h
> > > > +++ b/include/linux/usb/otg.h
> > > > @@ -121,5 +121,6 @@ enum usb_dr_mode {
> > > >  };
> > > >  
> > > >  extern enum usb_dr_mode usb_get_dr_mode(struct device *dev);
> > > > +extern enum usb_dr_mode usb_get_role_switch_default_mode(struct device *dev);
> > > 
> > > What other code outside of the dwc3 driver will ever need to call this?
> > I prepare a series of pathes for mtu3, and will support
> > "role-switch-default-mode" property
> 
> Ok, how about we wait until at least 2 drivers need it before accepting
> this change.
Makes sense, thank you
> 
> thanks,
> 
> greg k-h