Hi Brian, On Thu, 26 May 2016 14:05:30 -0700 Brian Norris <briannor...@chromium.org> wrote:
> It doesn't make sense to allow the duty cycle to be larger than the > period. I can see this behavior by, e.g.: > > # echo 1 > /sys/class/pwm/pwmchip0/export > # cat /sys/class/pwm/pwmchip0/pwm1/period > 100 > # echo 101 > /sys/class/pwm/pwmchip0/pwm1/duty_cycle > [... driver may or may not reject the value, or trigger some logic bug ...] > > It's better to see: > > # echo 1 > /sys/class/pwm/pwmchip0/export > # cat /sys/class/pwm/pwmchip0/pwm1/period > 100 > # echo 101 > /sys/class/pwm/pwmchip0/pwm1/duty_cycle > -bash: echo: write error: Invalid argument > > Signed-off-by: Brian Norris <briannor...@chromium.org> > --- > drivers/pwm/core.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > index dba3843c53b8..9246b60f894a 100644 > --- a/drivers/pwm/core.c > +++ b/drivers/pwm/core.c > @@ -463,6 +463,9 @@ int pwm_apply_state(struct pwm_device *pwm, struct > pwm_state *state) > if (!memcmp(state, &pwm->state, sizeof(*state))) > return 0; > > + if (state->duty_cycle > state->period) > + return -EINVAL; > + Argh, I forgot to move the pwm_config() checks [1] into pwm_apply_state() :-/. I think we should check all the corner cases (see this diff [2]), once done you can add my Acked-by: Boris Brezillon <boris.brezil...@free-electrons.com> Thierry, can you include that in your material for 4.7-rc1? Thanks, Boris [1]http://lxr.free-electrons.com/source/drivers/pwm/core.c#L443 [2]http://code.bulix.org/wtqja4-99473 -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com
