Hi Boris, On Fri, May 27, 2016 at 09:34:39AM +0200, Boris Brezillon wrote: > 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() :-/.
Oh, I didn't actually notice this was a regression. > I think we should check all the corner cases (see this diff [2]), Now that you mention it, I think you've also dropped some signed (negative value) checking in pwm_config(). I'll squash in your diff + some pwm_config() fixes. > once done you can add my > > Acked-by: Boris Brezillon <boris.brezil...@free-electrons.com> I'll send v2 without your ack, since I'm going to add a tiny bit extra. That'll give you a chance to ack the final (?) version. > Thierry, can you include that in your material for 4.7-rc1? That sounds like it would be a good idea, IMO. Thanks for noticing this was a regression! :) Regards, Brian > 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
