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

Claudiu Beznea
2018-01-22T09:00:15Z

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