Hi Trent,
On Sun, 5 Jul 2009 01:13:14 -0700 (PDT), Trent Piepho wrote:
> On Fri, 3 Jul 2009, Jean Delvare wrote:
> > Kernels 2.6.22 to 2.6.24 (inclusive) need some compatibility quirks
> > for the hrtimer API. For older kernels, some required functions were
> > not exported so there's nothing we can do. This means that drivers
> > using the hrtimer infrastructure will no longer work for kernels older
> > than 2.6.22.
> >
> > Signed-off-by: Jean Delvare <kh...@linux-fr.org>
> > ---
> > v4l/compat.h | 18 ++++++++++++++++++
> > 1 file changed, 18 insertions(+)
> >
> > --- a/v4l/compat.h
> > +++ b/v4l/compat.h
> > @@ -480,4 +480,22 @@ static inline unsigned long v4l_compat_f
> > }
> > #endif
> >
> > +/*
> > + * Compatibility code for hrtimer API
> > + * This will make hrtimer usable for kernels 2.6.22 and later.
> > + * For earlier kernels, not all required functions are exported
> > + * so there's nothing we can do.
> > + */
> > +
> > +#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 25) && \
> > + LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 22)
> > +#include <linux/hrtimer.h>
>
> Instead of including hrtimer.h from compat.h it's better if you check if it
> has already been included and only enable the compat code in that case.
> That way hrtimer doesn't get included for files that don't need it and
> might define something that conflicts with something from hrtimer. And it
> prevents someone from forgetting to include hrtimer when they needed it,
> but having the error masked because compat.h is doing it for them.
I see. But this will only work if compat.h is included after all
headers. If it always the case? I see for example that cx88-input
includes <media/ir-common.h> after "compat.h".
> > +/* Forward a hrtimer so it expires after the hrtimer's current now */
> > +static inline unsigned long hrtimer_forward_now(struct hrtimer *timer,
> > + ktime_t interval)
> > +{
> > + return hrtimer_forward(timer, timer->base->get_time(), interval);
> > +}
> > +#endif
> > +
> > #endif /* _COMPAT_H */
--
Jean Delvare
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