Re: [PATCH v2] Input: analog: Always use ktime functions

[Guenter Roeck]

On 9/7/21 2:40 AM, Geert Uytterhoeven wrote:
> Hi Günter,
>
> On Tue, Sep 7, 2021 at 8:35 AM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> > m68k, mips, s390, and sparc allmodconfig images fail to build with the
> > following error.
> >
> > drivers/input/joystick/analog.c:160:2: error:
> >          #warning Precise timer not defined for this architecture.
> >
> > Remove architecture specific time handling code and always use ktime
> > functions to determine time deltas. Also remove the now useless use_ktime
> > kernel parameter.
> >
> > Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> > ---
> > v2: Drop helper functions and use ktime_get() and ktime_sub() directly
> >      Drop 'speed' variable and use NSEC_PER_MSEC directly
> >
> >   drivers/input/joystick/analog.c | 103 ++++----------------------------
> >   1 file changed, 11 insertions(+), 92 deletions(-)
> >
> > diff --git a/drivers/input/joystick/analog.c b/drivers/input/joystick/analog.c
> > index f798922a4598..a9ec41f48068 100644
> > --- a/drivers/input/joystick/analog.c
> > +++ b/drivers/input/joystick/analog.c
>
> > @@ -275,7 +210,7 @@ static int analog_cooked_read(struct analog_port *port)
> >                  this |= data[i];
> >                  for (j = 0; j < 4; j++)
> >                          if (data[i] & (1 << j))
> > -                               port->axes[j] = (delta(start, time[i]) << ANALOG_FUZZ_BITS) / port->loop;
> > +                               port->axes[j] = (ktime_sub(time[i], start) << ANALOG_FUZZ_BITS) / port->loop;
>
> This is now a 64-by-32 division, triggering undefined references to __udivdi3
> on some 32-bit platforms.

And I was sure I checked for those. Oh well. I'll send v3 later today.

> Assumed deltas are small, the simple solution of truncating to
> 32 bit (like delta() did before):
>
> -  port->axes[j] = (ktime_sub(time[i], start) << ANALOG_FUZZ_BITS) / port->loop;
> + port->axes[j] = ((u32)ktime_sub(time[i], start) << ANALOG_FUZZ_BITS)
> / port->loop;

Yes, I'll do that.

Thanks,
Guenter