Re: [PATCH 1/3] clocksource: timer-dm: Check prescaler value

Ladislav Michl
2018-01-22T09:59:55Z

On Mon, Jan 22, 2018 at 11:00:15AM +0200, Claudiu Beznea wrote:
>
>
> On 17.01.2018 23:47, Ladislav Michl wrote:
> > Invalid value silently disables use of the prescaler.
> > Use -1 explicitely for that purpose and error out on
> > invalid value.
> >
> > Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
> > ---
> > drivers/clocksource/timer-dm.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/clocksource/timer-dm.c b/drivers/clocksource/timer-dm.c
> > index 60db1734ea3b..324ec93d3dd2 100644
> > --- a/drivers/clocksource/timer-dm.c
> > +++ b/drivers/clocksource/timer-dm.c
> > @@ -663,13 +663,13 @@ int omap_dm_timer_set_prescaler(struct omap_dm_timer *timer, int prescaler)
> > {
> > u32 l;
> >
> > - if (unlikely(!timer))
> > + if (unlikely(!timer) || prescaler < -1 || prescaler > 7)
> You are checking the prescaller here to be in [0, 7] interval.

You mean [-1, 7] I suppose.

> > return -EINVAL;
> >
> > omap_dm_timer_enable(timer);
> > l = omap_dm_timer_read_reg(timer, OMAP_TIMER_CTRL_REG);
> > l &= ~(OMAP_TIMER_CTRL_PRE | (0x07 << 2));
> > - if (prescaler >= 0x00 && prescaler <= 0x07) {
> > + if (prescaler >= 0) {
> Is this check still necessary?

Yes, as we need also some way to disable prescaler, see commit message.

> > l |= OMAP_TIMER_CTRL_PRE;
> > l |= prescaler << 2;
> > }

Best regards,
ladis