RE: [RFC] [PATCH] digital compass hmc5843

From: Datta, Shubhrajyoti
Date: Fri Jul 02 2010 - 06:53:56 EST


>
> <snip>
> >
> > I think that having a Hz as units will have its own issues. First the
> decimal implementation. However I am open to the implementation.
> > Also do you know of a driver that takes care of this.
> None of the current drivers go below 1Hz so not quite the same.
> lis3l02dq (accelerometer) does the match against a list, but it
> is done numerically rather than via string matches as would be needed
> here.
> >
> >>
> >> static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("0.5 1 2 5 10 20 50");
> >>
> >>
> >> Then strncmp with the options to set the value up. The rounding
> approach
> >> gets tricky with a non integer value so probably easier to only allow
> >> these
> >> values.

What is a recommended way of getting a double or float
Is there any Strict_srttod etc.

> >
> > Allowing only this value will result in default/ reject case and will
> keep the previous value, may confuse the application
> Then the application is ignoring the interface spec that says it must read
> _available files if they are there.
> This way the rounding behaviour is left to userspace and what the
> application prefers rather
> than in kernel actually making it the most flexible option.

Agree
> >
> >>
> >>> +static IIO_DEV_ATTR_AVAIL_SAMP_FREQ(show_avail_samp_freq);
> >>> +
> >>> +static s32 hmc5843_set_rate(struct i2c_client *client,
> >>> + u8 rate)
> >>> +{
> >>> + struct hmc5843_data *data = i2c_get_clientdata(client);
> >>> + u8 reg_val;
> >>> +
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