From mboxrd@z Thu Jan 1 00:00:00 1970 From: boris.brezillon@free-electrons.com (Boris Brezillon) Date: Tue, 17 May 2016 13:11:47 +0200 Subject: [PATCH] pwm: Fill pwm->args before calling pwm_request_from_chip() In-Reply-To: <20160517110438.GB26166@ulmo.ba.sec> References: <1463481333-23438-1-git-send-email-boris.brezillon@free-electrons.com> <1463481333-23438-2-git-send-email-boris.brezillon@free-electrons.com> <20160517110438.GB26166@ulmo.ba.sec> Message-ID: <20160517131147.7f505f2b@bbrezillon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, 17 May 2016 13:04:38 +0200 Thierry Reding wrote: > On Tue, May 17, 2016 at 12:35:33PM +0200, Boris Brezillon wrote: > [...] > > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > > index 427142d..3d2eeaa 100644 > > --- a/drivers/pwm/core.c > > +++ b/drivers/pwm/core.c > > @@ -143,10 +143,6 @@ of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args) > > if (args->args[0] >= pc->npwm) > > return ERR_PTR(-EINVAL); > > > > - pwm = pwm_request_from_chip(pc, args->args[0], NULL); > > - if (IS_ERR(pwm)) > > - return pwm; > > - > > pwm->args.period = args->args[1]; > > > > if (args->args[2] & PWM_POLARITY_INVERTED) > > @@ -154,6 +150,10 @@ of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args) > > else > > pwm->args.polarity = PWM_POLARITY_NORMAL; > > > > + pwm = pwm_request_from_chip(pc, args->args[0], NULL); > > + if (IS_ERR(pwm)) > > + return pwm; > > + > > Can't do that, because now you're dereferencing an uninitialized > pointer. Yes, forget this patch, it's not needed anyway since all PWM users are now directly calling pwm_apply_args() after requesting the PWM. The bad news is I broke bisectibilty :-(. Still does not explain the bug reported by Mika. -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com