Re: [PATCH RFC 3/4] input: add a EV_SW event for ratchet switch

[Peter Hutterer <peter.hutterer@who-t.net>]

On Mon, Mar 27, 2017 at 09:27:31AM -0300, Mauro Carvalho Chehab wrote:
> Em Mon, 27 Mar 2017 11:53:57 +1000
> Peter Hutterer <peter.hutterer@who-t.net> escreveu:
> 
> > On Sat, Mar 25, 2017 at 07:49:41PM -0300, Mauro Carvalho Chehab wrote:
> > > Some mouses have a switch on their wheel, allowing to switch
> > > between ratchet or free wheel mode. Add support for it.  
> > 
> > I understand the want to support it because it's there but what do you
> > expect this to be used for?
> > 
> > tbh, I wouldn't know what to do with this information, short of displaying
> > some OSD to inform the user. Which is rather superfluous since the physical
> > change will feel obvious anyway.
> 
> For this particular device, the main reason is because it is there :-)
> As adding support for it is trivial, I don't see any reason why not
> adding it.
> 
> Yet, applications could use it, in order to switch between a "discrete" 
> mode, where one wheel position corresponds to one line of scroll, and
> movements below a threshold would be ignored.

fwiw, that would more likely be the  result of receiving a different event
code (hires-wheel), more so than a ratchet switch - at least on this device.

the mice I have here don't change the behaviour of the wheel, so the
granularity is the same before and after. But they also don't send events
for the state, so there's that :)

Cheers,
   Peter
> 
> 
> > 
> > A Documentation/input/event-codes.txt hunk would be welcomed here too
> > btw.
> 
> Sure. Will do on a next patch series, once we agree about the high
> resolution wheel movements API.
> > 
> > Cheers,
> >    Peter
> > 
> > > 
> > > Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
> > > ---
> > >  include/linux/mod_devicetable.h        | 2 +-
> > >  include/uapi/linux/input-event-codes.h | 4 +++-
> > >  2 files changed, 4 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> > > index 8a57f0b1242d..73534c591b40 100644
> > > --- a/include/linux/mod_devicetable.h
> > > +++ b/include/linux/mod_devicetable.h
> > > @@ -292,7 +292,7 @@ struct pcmcia_device_id {
> > >  #define INPUT_DEVICE_ID_LED_MAX		0x0f
> > >  #define INPUT_DEVICE_ID_SND_MAX		0x07
> > >  #define INPUT_DEVICE_ID_FF_MAX		0x7f
> > > -#define INPUT_DEVICE_ID_SW_MAX		0x0f
> > > +#define INPUT_DEVICE_ID_SW_MAX		0x1f
> > >  
> > >  #define INPUT_DEVICE_ID_MATCH_BUS	1
> > >  #define INPUT_DEVICE_ID_MATCH_VENDOR	2
> > > diff --git a/include/uapi/linux/input-event-codes.h b/include/uapi/linux/input-event-codes.h
> > > index 23b2d377af59..a3eafd0527f1 100644
> > > --- a/include/uapi/linux/input-event-codes.h
> > > +++ b/include/uapi/linux/input-event-codes.h
> > > @@ -782,7 +782,9 @@
> > >  #define SW_LINEIN_INSERT	0x0d  /* set = inserted */
> > >  #define SW_MUTE_DEVICE		0x0e  /* set = device disabled */
> > >  #define SW_PEN_INSERTED		0x0f  /* set = pen inserted */
> > > -#define SW_MAX			0x0f
> > > +#define SW_RATCHET		0x10  /* set = ratchet mode,
> > > +					 unset: free wheel */
> > > +#define SW_MAX			0x1f
> > >  #define SW_CNT			(SW_MAX+1)
> > >  
> > >  /*
> > > -- 
> > > 2.9.3
> > > 
> > >   
> 
> 
> 
> Thanks,
> Mauro