On 21/01/21 8:07 am, Mark Brown wrote:
> On Wed, Jan 20, 2021 at 12:41:18PM +1300, Eliot Blennerhassett wrote:
>
> It would be a bit easier to have one discussion per mail
taking up the topic of ak4458 reset polarity alone
ak4458.txt documents:
Optional properties:
- reset-gpios: A GPIO specifier for the power down & reset pin
Example
reset-gpios = <&gpio1 10 GPIO_ACTIVE_LOW>
Existing code in ak4458.c:
static void ak4458_power_off(struct ak4458_priv *ak4458)
{
if (ak4458->reset_gpiod) {
gpiod_set_value_cansleep(ak4458->reset_gpiod, 0);
usleep_range(1000, 2000);
}
}
I suspect the value 0 represents the raw value for an active-low gpio,
but this is wrong when used with gpiod_set_value_cansleep() function
whose doc says "Set the logical value of the GPIO, i.e. taking its
ACTIVE_LOW status into account"
Setting the value to 0 makes the GPIO *inactive* i.e. high if it is
specified in the DT as ACTIVE_LOW. This is the wrong way round for the
power_off/on functions.
Because the DT property is optional, perhaps nobody has tried to use it
until now?
Patch to follow
--
Eliot
