Subject: [PATCH v2 03/15] watchdog: orion: Use atomic access for shared registers

From: [email-masked] (Ezequiel Garcia)
Date: Tue, 21 Jan 2014 06:42:15 -0300

On Tue, Jan 21, 2014 at 07:19:52AM -0200, Fabio Estevam wrote:
> On Tue, Jan 21, 2014 at 7:12 AM, Ezequiel Garcia
> <[email-masked]> wrote:
> > Since the timer control register is shared with the clocksource driver,
> > use the recently introduced atomic_io_clear_set() to access such register.
> >
> > Signed-off-by: Ezequiel Garcia <[email-masked]>
> > ---
> >  drivers/watchdog/orion_wdt.c | 20 ++++----------------
> >  1 file changed, 4 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/watchdog/orion_wdt.c b/drivers/watchdog/orion_wdt.c
> > index f7722a4..cf64510 100644
> > --- a/drivers/watchdog/orion_wdt.c
> > +++ b/drivers/watchdog/orion_wdt.c
> > @@ -61,8 +61,6 @@ static int orion_wdt_ping(struct watchdog_device *wdt_dev)
> >
> >  static int orion_wdt_start(struct watchdog_device *wdt_dev)
> >  {
> > -       u32 reg;
> > -
> >         spin_lock(&wdt_lock);
> 
> Shouldn't this spin_lock be dropped now?
> 

Hm... yes. The watchdog core uses a mutex to serialize all the watchdog hooks:
start, stop, ping, set_timeout, etc. So it seems you're right, the spinlock
should be dropped entirely as I see no need for it.

Thanks for the feedback,
-- 
Ezequiel Garc?a, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com