Re: [PATCH] iio: frequency: New driver for Analog Devices ADF4350/ADF4351 Wideband Synthesizers

[Michael Hennerich <michael.hennerich@analog.com>]

On 05/10/2012 02:36 PM, Jonathan Cameron wrote:
> On 5/8/2012 4:34 PM, Michael Hennerich wrote:
>> On 05/08/2012 04:51 PM, Jonathan Cameron wrote:
>>> On 5/7/2012 2:49 PM, michael.hennerich@analog.com wrote:
>>>> From: Michael Hennerich<michael.hennerich@analog.com>
>>>>
>>>>
>>>> +
>>>> +static const struct iio_chan_spec_ext_info adf4350_ext_info[] = {
>>>> + /* Ideally we use IIO_CHAN_INFO_FREQUENCY, but there are
>>>> + * values>  2^32 in order to support the entire frequency range
>>>> + * in Hz. Using scale is a bit ugly.
>>>> + */
>>> hmm.. Add IIO_VAL_MEGA_PLUS_INT.. We were always going to need a bigger
>>> version at somepoint...
>> Well - we then need an s64, however read|write_raw feature s32 for
>> val and val2. So shall we pass low word in val and high word in val2?
> I was thinking
> val*1e6 + val2 would fit with what we have done elsewhere?  Is that
> enough room?
Hi Jonathan,

IIO_VAL_MEGA_PLUS_INT versus IIO_VAL_LONG_LONG

It is enough room. But I wonder why we would do costly divide and modulus operations, when we can do sifts and ANDs? Splitting a s64 would give is the maximum available room with very little overhead.

Thoughts?

-- 
Greetings,
Michael

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