linux-kernel - Re: [PATCH v8 1/3] serdev: Add method to assert break signal over tty UART port

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Message-ID: <AM9PR04MB8603EDB41582B5B816993B12E7B89@AM9PR04MB8603.eurprd04.prod.outlook.com>
Date:   Sun, 12 Mar 2023 07:01:17 +0000
From:   Neeraj sanjay kale <neeraj.sanjaykale@....com>
To:     Simon Horman <simon.horman@...igine.com>
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Subject: Re: [PATCH v8 1/3] serdev: Add method to assert break signal over tty
 UART port

Hi Simon

> 
> On Fri, Mar 10, 2023 at 11:49:19PM +0530, Neeraj Sanjay Kale wrote:
> > Adds serdev_device_break_ctl() and an implementation for ttyport.
> > This function simply calls the break_ctl in tty layer, which can
> > assert a break signal over UART-TX line, if the tty and the underlying
> > platform and UART peripheral supports this operation.
> >
> > Signed-off-by: Neeraj Sanjay Kale <neeraj.sanjaykale@....com>
> > ---
> > v3: Add details to the commit message. (Greg KH)
> 
> ...
> 
> > diff --git a/include/linux/serdev.h b/include/linux/serdev.h index
> > 66f624fc618c..c065ef1c82f1 100644
> > --- a/include/linux/serdev.h
> > +++ b/include/linux/serdev.h
> 
> ...
> 
> > @@ -255,6 +257,10 @@ static inline int serdev_device_set_tiocm(struct
> > serdev_device *serdev, int set,  {
> >       return -ENOTSUPP;
> >  }
> > +static inline int serdev_device_break_ctl(struct serdev_device
> > +*serdev, int break_state) {
> > +     return -EOPNOTSUPP;
> 
> Is the use of -EOPNOTSUPP intentional here?
> I see -ENOTSUPP is used elsewhere in this file.
I was suggested to use - EOPNOTSUPP instead of - ENOTSUPP by the check patch scripts and by Leon Romanovsky.
https://patchwork.kernel.org/project/bluetooth/patch/20230130180504.2029440-2-neeraj.sanjaykale@nxp.com/

ENOTSUPP is not a standard error code and should be avoided in new patches.
See: https://lore.kernel.org/netdev/20200510182252.GA411829@lunn.ch/

> 
> > +}
> >  static inline int serdev_device_write(struct serdev_device *sdev, const
> unsigned char *buf,
> >                                     size_t count, unsigned long
> > timeout)  {
> > --
> > 2.34.1
> >

Thanks,
Neeraj