On 21, April 2018 18:55, Jonathan Cameron wrote:
> On Fri, 20 Apr 2018 21:30:32 +0200
> David Veenstra <davidjulianveenstra@xxxxxxxxx> wrote:
>
>> The manual states that the data is contained in the upper 12 bits
>> of the 16 bits read by spi. The code that extracts these 12 bits
>> is correct for both be and le machines, but this is not clear
>> from a first glance.
>>
>> To improve readability the relevant expressions are replaced
>> with equivalent expressions that use be16_to_cpup.
>>
>> Signed-off-by: David Veenstra <davidjulianveenstra@xxxxxxxxx>
>> ---
>> drivers/staging/iio/resolver/ad2s1200.c | 9 ++++-----
>> 1 file changed, 4 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/staging/iio/resolver/ad2s1200.c b/drivers/staging/iio/resolver/ad2s1200.c
>> index 0a5fc9917e32..11ed9c7332e6 100644
>> --- a/drivers/staging/iio/resolver/ad2s1200.c
>> +++ b/drivers/staging/iio/resolver/ad2s1200.c
>> @@ -57,7 +57,7 @@ static int ad2s1200_read_raw(struct iio_dev *indio_dev,
>> {
>> struct ad2s1200_state *st = iio_priv(indio_dev);
>> int ret = 0;
>> - s16 vel;
>> + u16 vel;
>>
>> mutex_lock(&st->lock);
>> gpio_set_value(st->sample, 0);
>> @@ -73,14 +73,13 @@ static int ad2s1200_read_raw(struct iio_dev *indio_dev,
>> return ret;
>> }
>>
>> + vel = be16_to_cpup((__be16 *)st->rx);
> Well it isn't vel (velocity) in one case so now the name is misleading.
>
> Also that type cast suggests a fairly obvious cleanup associated with this one.
> Why not make st->rx a __be16 in the first pace avoiding the need to cast at all?
>
> Then you could just have *val = be16_to_cpu(st->rx) >> 4 and similar.
Agreed on naming of vel, and type of st-rx. I'll change this for v3.
Best regards,
David Veenstra
>
>> switch (chan->type) {
>> case IIO_ANGL:
>> - *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
>> + *val = vel >> 4;
>> break;
>> case IIO_ANGL_VEL:
>> - vel = (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
>> - vel = sign_extend32(vel, 11);
>> - *val = vel;
>> + *val = sign_extend32((s16)vel >> 4, 11);
> If you were to use an intermediate that was s16 then the sign extend would
> be automatic. Perhaps it is clear to do it like this though..
> Up to you.
>
>> break;
>> default:
>> mutex_unlock(&st->lock);
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