Resend, previous mail was erroneously sent in HTML. I apologize for the
spamming.
On 6/23/24 17:45, Jonathan Cameron wrote:
> On Tue, 18 Jun 2024 14:02:40 +0000
> Guillaume Stols <gstols@xxxxxxxxxxxx> wrote:
>> gpiod_set_array_value was misused here: the implementation relied on the
>> assumption that an unsigned long was required for each gpio, while the
>> function expects a bit array stored in "as much unsigned long as needed
>> for storing one bit per GPIO", i.e it is using a bit field.
>>
>> Fixes: d2a415c86c6b ("iio: adc: ad7606: Add support for AD7606B ADC")
>> Signed-off-by: Guillaume Stols <gstols@xxxxxxxxxxxx>
> Always drag fixes to the start of a series. Probably doesn't matter
> in this case but we want it to be obvious there are no necessary
precursors
> in this series for anyone backporting.
OK will do this change in the next version.
>
> What is the user visible outcome of this bug? Superficially the numbers
> all end up the same I think even though the code is clearly working
> mostly by luck. So might not warrant a fixes tag?
This is leading into some issues I should maybe have better documented
in the commit message.
See below
>
>> ---
>> drivers/iio/adc/ad7606.c | 4 ++--
>> drivers/iio/adc/ad7606_spi.c | 5 +++--
>> 2 files changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
>> index e3426287edf6..502344e019e0 100644
>> --- a/drivers/iio/adc/ad7606.c
>> +++ b/drivers/iio/adc/ad7606.c
>> @@ -235,9 +235,9 @@ static int ad7606_write_os_hw(struct iio_dev
*indio_dev, int val)
>> struct ad7606_state *st = iio_priv(indio_dev);
>> DECLARE_BITMAP(values, 3);
>> - values[0] = val;
>> + values[0] = val & GENMASK(2, 0);
>> - gpiod_set_array_value(ARRAY_SIZE(values), st->gpio_os->desc,
>> + gpiod_set_array_value(st->gpio_os->ndescs, st->gpio_os->desc,
>> st->gpio_os->info, values);
ARRAY_SIZE(values) is 1 because DECLARE_BITMAP will declare a dimension
1 unsigned long array (more than enough for 3 bits !).
We want to set 3 bits in gpiod_set_array_value, thus the first parameter
should be 3, not 1.
>> /* AD7616 requires a reset to update value */
>> diff --git a/drivers/iio/adc/ad7606_spi.c b/drivers/iio/adc/ad7606_spi.c
>> index 263a778bcf25..287a0591533b 100644
>> --- a/drivers/iio/adc/ad7606_spi.c
>> +++ b/drivers/iio/adc/ad7606_spi.c
>> @@ -249,8 +249,9 @@ static int ad7616_sw_mode_config(struct iio_dev
*indio_dev)
>> static int ad7606B_sw_mode_config(struct iio_dev *indio_dev)
>> {
>> struct ad7606_state *st = iio_priv(indio_dev);
>> - unsigned long os[3] = {1};
>> + DECLARE_BITMAP(os, 3);
>> + bitmap_fill(os, 3);
Here we need 3 bits set HIGH in one unsigned long (i.e 0x07) and we get
3 times 0x01 instead.
Thus, it will not switch to software mode if OS pins are not hardwired
(which is I must admit, rather unlikely).
>> /*
>> * Software mode is enabled when all three oversampling
>> * pins are set to high. If oversampling gpios are defined
>> @@ -258,7 +259,7 @@ static int ad7606B_sw_mode_config(struct iio_dev
*indio_dev)
>> * otherwise, they must be hardwired to VDD
>> */
>> if (st->gpio_os) {
>> - gpiod_set_array_value(ARRAY_SIZE(os),
>> + gpiod_set_array_value(st->gpio_os->ndescs,
>> st->gpio_os->desc, st->gpio_os->info, os);
>> }
>> /* OS of 128 and 256 are available only in software mode */
>>
