Re: [PATCH v4 2/3] tty: add new helper function tty_get_tiocm

[Florian Eckert]

On 2023-10-21 18:15, Greg KH wrote:
> On Thu, Oct 19, 2023 at 01:28:08PM +0200, Florian Eckert wrote:
> > The struct 'tty_struct' has a callback to read the status flags of the 
> > tty
> > if the tty driver provides them. So fare, the data is transferred 
> > directly
> > to userspace with the function 'tty_tiocmget'. This function cannot be
> > used to evaluate the status line of the tty interface in the 
> > ledtrig-tty
> > trigger. To make this possible, a new function must be added that does
> > not immediately pass the data on to userspace.
> >
> > The new function 'tty_get_tiocm' only returns the status register.
> > This information can then be processed further in the ledtrig-tty
> > trigger.
>
> Writing changelogs are hard.  You are including a lot of information in
> here that really doesn't need to be, as you are focusing on your
> specific use case, which is fine, but you are creating a generic
> function.

Yes, that is absolutely right. I'll try to take that into account next
time, thanks for your advice.

> This can be simpler, how about something like this:
>
> 	There is no in-kernel function to get the status register of a
> 	tty device like the TIOCMGET ioctl returns to userspace.  Create
> 	a new function, tty_get_tiocm(), to obtain the status register
> 	that other portions of the kernel can call if they need this
> 	information, and move the existing internal tty_tiocmget()
> 	function to use this interface.

I will replace the commit message with your suggestion in the next round 
of
the patch series. Thanks!

---
Florian