Hello Daniel,
On Tue, Jan 21, 2014 at 10:57:37AM +0100, Daniel Lezcano wrote:
> On 01/21/2014 10:12 AM, Ezequiel Garcia wrote:
> > Replace the driver-specific thread-safe shared register API
> > by the recently introduced atomic_io_clear_set().
> >
> > Signed-off-by: Ezequiel Garcia <ezequiel.garcia@xxxxxxxxxxxxxxxxxx>
>
> in the future, put me in Cc when modifying files in clocksource that
> will make my life easier to track the changes.
>
Ouch, sorry about that.
[..]
> > /*
> > * Free-running clocksource handling.
> > @@ -68,7 +54,8 @@ static int orion_clkevt_next_event(unsigned long delta,
> > {
> > /* setup and enable one-shot timer */
> > writel(delta, timer_base + TIMER1_VAL);
> > - orion_timer_ctrl_clrset(TIMER1_RELOAD_EN, TIMER1_EN);
> > + atomic_io_modify(timer_base + TIMER_CTRL,
> > + TIMER1_RELOAD_EN | TIMER1_EN, TIMER1_EN);
>
> I am not convinced this change is worth.
>
> Could you elaborate the race the spinlock should prevent ?
>
Sure. Take a look to the patchset that adds the atomic I/O (sorry again for
not Ccing you on that one):
http://www.spinics.net/lists/arm-kernel/msg292775.html
The TIMER_CTRL register provides clocksource and watchdog control, so we
need a safe way to access the register, since we're sharing it on two
completely unrelated drivers.
--
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com
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