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SubjectRe: [rtc-linux] Re: [PATCH 1/7] Blackfin RTC driver: the frequency function is in units of Hz, not units of seconds, so lock our driver down to 1 Hz
On Dec 4, 2007 11:41 AM, Alessandro Zummo <alessandro.zummo@towertech.it> wrote:
> On Tue, 4 Dec 2007 11:29:11 -0500 "Mike Frysinger" <vapier.adi@gmail.com> wrote:
> > On Dec 4, 2007 11:26 AM, Alessandro Zummo <alessandro.zummo@towertech.it> wrote:
> > > Bryan Wu <bryan.wu@analog.com> wrote:
> > >
> > > Hi, I fannly got some time to review the patches. Seems ok, the
> > > only question is...
> > >
> > > > static int bfin_irq_set_freq(struct device *dev, int freq)
> > > > {
> > > > - struct bfin_rtc *rtc = dev_get_drvdata(dev);
> > > > stampit();
> > > > - rtc->rtc_dev->irq_freq = freq;
> > > > - return 0;
> > > > + return -ENOTTY;
> > > > }
> > >
> > > .. why ENOTTY here?
> >
> > that's what the documentation says to do as does every other rtc driver ?
>
> it should be EINVAL. at least it is wat rtc-cmos does when the value
> is invalid.

the return of ENOTTY is to say "changing of freq isnt supported", not
that the value is invalid. but i can get the same behavior by
deleting the function as the rtc-dev layer will take care of returning
ENOTTY.

so the behavior is for the RTC_IRQP_SET ioctl:
- return ENOTTY if you cannot change freq
- the rtc-dev layer will do this for you if you do not set irq_set_freq
- return EINVAL if the requested freq is not within the capabilities
of the hardware

sound about right ?
-mike


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