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SubjectRe: [PATCH v2 1/2] iio: gyro: Add driver support for ADXRS290
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On 22/07/20 3:08 am, Andy Shevchenko wrote:
> On Tue, Jul 21, 2020 at 11:35 PM Nishant Malpani
> <nish.malpani25@gmail.com> wrote:
>> On 22/07/20 1:16 am, Andy Shevchenko wrote:
>>> On Tue, Jul 21, 2020 at 9:20 PM Nishant Malpani
>>> <nish.malpani25@gmail.com> wrote:
>
> ...
>
>>>> + *vals = (const int *)adxrs290_lpf_3db_freq_tbl;
>>>
>>> Why casting?
>>>
>> adxrs290_lpf_3db_freq_tbl is of type (int *)[2], right? Without the
>> casting, an incompatible-pointer-type error is thrown.
>>
>>> ...
>>>
>>>> + *vals = (const int *)adxrs290_hpf_3db_freq_tbl;
>>>
>>> Ditto.
>>>
>> See above comment.
>
> Can't you declare table as const int?
>
I'm not sure I understand you completely here; do you mean const int *?
So, an array of alternate integer and fractional parts? I suppose that's
possible but we'd be introducing unwanted complexity I feel - for
example, currently the index of the 3db frequency in the table is used
to directly map & set bits in the filter register corresponding to that
frequency but with the approach you share, we'd have to apply a
transformation (div by 2) to set the same bits in the filter register.
Do you think the added complexity justifies the removal of the casting?

> ...
>
>>>> + /* max transition time to measurement mode */
>>>> + msleep_interruptible(ADXRS290_MAX_TRANSITION_TIME_MS);
>>>
>>> I'm not sure what the point of interruptible variant here?
>>>
>> I referred Documentation/timers/timers-howto.rst for this.
>> My reasoning was shaped to use the interruptible variant because the
>> transition settles in a time *less than* 100ms and since 100ms is quite
>> a huge time to sleep, it should be interrupted in case a signal arrives.
>
> This is probe of the device,
> What are the expectations here?
>
I fail to understand why this can't be used in the probe() but perhaps
in a routine to standby/resume. Could you please elaborate?

With regards,
Nishant Malpani

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