Re: [PATCH 07/16] iio: adc: at91-sama5d2_adc: simplify the code in at91_adc_read_info_raw()

Jonathan Cameron
2022-06-11T17:45:00Z

On Thu, 9 Jun 2022 11:32:04 +0300
Claudiu Beznea <claudiu.beznea@microchip.com> wrote:

> Simplify a bit the code in at91_adc_read_info_raw() by reducing the
> number of lines of code.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>

I'm not convinced this is worth while, but there are some lesser
steps visible in this patch that probably are.

Given your earlier reorg to move at01_adc_adjust_val_osr() under the locks,
you can now move the locks to the caller, thus not needing to handle them
separately in all the exit paths.

> ---
> drivers/iio/adc/at91-sama5d2_adc.c | 35 +++++++++---------------------
> 1 file changed, 10 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index b52f1020feaf..fbb98e216e70 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -1576,6 +1576,7 @@ static int at91_adc_read_info_raw(struct iio_dev *indio_dev,
> struct iio_chan_spec const *chan, int *val)
> {
> struct at91_adc_state *st = iio_priv(indio_dev);
> + int (*fn)(struct at91_adc_state *, int, u16 *) = NULL;
> u16 tmp_val;
> int ret;
>
> @@ -1583,29 +1584,18 @@ static int at91_adc_read_info_raw(struct iio_dev *indio_dev,
> * Keep in mind that we cannot use software trigger or touchscreen
> * if external trigger is enabled
> */
> - if (chan->type == IIO_POSITIONRELATIVE) {
> - ret = iio_device_claim_direct_mode(indio_dev);
> - if (ret)
> - return ret;

You can drop this out of the if statements as it happens in all paths.
Or even better, move it to the caller..

> - mutex_lock(&st->lock);
> -
> - ret = at91_adc_read_position(st, chan->channel,
> - &tmp_val);

huh? ret not checked?

> - *val = tmp_val;
> - ret = at91_adc_adjust_val_osr(st, val);
Sure this is duplicated, but meh it's only a few lines.

> - mutex_unlock(&st->lock);
> - iio_device_release_direct_mode(indio_dev);

this early release (compared to the long path) is the only bit really
gets duplicated in all paths..

> + if (chan->type == IIO_POSITIONRELATIVE)
> + fn = at91_adc_read_position;
> + if (chan->type == IIO_PRESSURE)
> + fn = at91_adc_read_pressure;
>
> + ret = iio_device_claim_direct_mode(indio_dev);
> + if (ret)
> return ret;
> - }
> - if (chan->type == IIO_PRESSURE) {
this should always have been an else if () as the chan->type couldn't be both.

> - ret = iio_device_claim_direct_mode(indio_dev);
> - if (ret)
> - return ret;
> - mutex_lock(&st->lock);
hence this lot can be shared with the above.

> + mutex_lock(&st->lock);
>
> - ret = at91_adc_read_pressure(st, chan->channel,
> - &tmp_val);
> + if (fn) {
> + ret = fn(st, chan->channel, &tmp_val);
> *val = tmp_val;
> ret = at91_adc_adjust_val_osr(st, val);
> mutex_unlock(&st->lock);
> @@ -1616,11 +1606,6 @@ static int at91_adc_read_info_raw(struct iio_dev *indio_dev,
>
> /* in this case we have a voltage channel */
>
> - ret = iio_device_claim_direct_mode(indio_dev);
> - if (ret)
> - return ret;
> - mutex_lock(&st->lock);
> -
> st->chan = chan;
>
> at91_adc_cor(st, chan);