Re: [PATCH v3] USB: serial: usb_wwan: replace DTR/RTS magic numbers with macros

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Sun, Jul 24, 2022 at 04:07:17PM +0200, Johan Hovold wrote:
> On Sun, Jul 24, 2022 at 03:50:52PM +0200, Greg Kroah-Hartman wrote:
> > On Sun, Jul 24, 2022 at 11:10:22AM +0200, Johan Hovold wrote:
> > > On Fri, Jul 22, 2022 at 04:50:40PM +0800, Yan Xinyu wrote:
> > > > The usb_wwan_send_setup function generates DTR/RTS signals in compliance
> > > > with CDC ACM standard. This patch changes magic numbers in this function
> > > > to equivalent macros.
> > > > 
> > > > Signed-off-by: Yan Xinyu <sdlyyxy@bupt.edu.cn>
> > > > ---
> > > > v1->v2:
> > > >  * Fix Signed-off-by name.
> > > > v2->v3:
> > > >  * Use already defined ACM_CTRL_DTR and ACM_CTRL_RTS in drivers/usb/class/cdc-acm.h
> > > > ---
> > > >  drivers/usb/serial/usb_wwan.c | 11 +++++++----
> > > >  1 file changed, 7 insertions(+), 4 deletions(-)
> > > > 
> > > > diff --git a/drivers/usb/serial/usb_wwan.c b/drivers/usb/serial/usb_wwan.c
> > > > index dab38b63eaf7..5c8303bd3676 100644
> > > > --- a/drivers/usb/serial/usb_wwan.c
> > > > +++ b/drivers/usb/serial/usb_wwan.c
> > > > @@ -29,8 +29,10 @@
> > > >  #include <linux/bitops.h>
> > > >  #include <linux/uaccess.h>
> > > >  #include <linux/usb.h>
> > > > +#include <linux/usb/cdc.h>
> > > >  #include <linux/usb/serial.h>
> > > >  #include <linux/serial.h>
> > > > +#include "../class/cdc-acm.h"
> > > 
> > > If we are to use common defines, these would need to be added to
> > > linux/usb/cdc.h first (parts of which are exposed to user space).
> > > 
> > > Note that we already have at least three copies of these defines in the
> > > tree.
> > > 
> > > I'm fine with adding another copy for now and not have to deal with with
> > > naming and cross driver updates. What do you think, Greg?
> > 
> > I think Yan should write a patch series to unify these and make it
> > right, instead of just papering over it all.
> 
> Ok, I just fear it will be more work for us since that involves
> decisions like whether it should be added to the uapi header, and then
> we get into naming, etc. But we're in no rush.
> 
> > Also this "../" stuff in a
> > #include directive is not ok, I wouldn't recommend this change be taken
> > as-is.
> 
> That was never an option, but I'd be ok with taking the v2 which added
> defines for the constants directly in the driver.

These are global defines, in a public spec, and they should all just be
in one place in the kernel.  What's wrong with include/uapi/linux/cdc.h
which is where the other ACM defined values are at?

thanks,

greg k-h