On 18.01.24 17:04, Mark Brown wrote:
> On Thu, Jan 18, 2024 at 04:30:37PM +0100, Javier Carrasco wrote:
>> On 18.01.24 14:49, Mark Brown wrote:
>>> On Mon, Jan 15, 2024 at 09:02:25PM +0100, Javier Carrasco wrote:
>
>>>> +static int cc2_enable(struct cc2_data *data)
>>>> +{
>>>> + int ret;
>
>>>> + if (regulator_is_enabled(data->regulator))
>>>> + return 0;
>
>>> This is generally a sign that the regulator API usage is not good, the
>>> driver should not rely on references to the regulator held by anything
>>> else since whatever else is holding the regulator on could turn it off
>>> at any time. If the driver did the enable itself then it should know
>>> that it did so and not need to query.
>
>> The driver handles a dedicated regulator, but I wanted to account for
>> the cases where the attempts to enable and disable the regulator fail
>> and keep parity. If the disabling attempt fails, will the regulator not
>> stay enabled? In that case, an additional call to regulator_enable would
>> not be required, right?
>> That is the only reason I am using regulator_is_enabled(), but maybe
>> things don't work like that.
>
> With exclusive use you can get away with this, you should have a comment
> for that case though.
>
I will add a comment to clarify it.
>>>> + ret = regulator_enable(data->regulator);
>>>> + if (ret < 0)
>>>> + return ret;
>>>> +
>>>> + /*
>>>> + * TODO: the startup-delay-us property of the regulator might be
>>>> + * added to the delay (if provided).
>>>> + * Currently there is no interface to read its value apart from
>>>> + * a direct access to regulator->rdev->constraints->enable_time,
>>>> + * which is discouraged like any direct access to the regulator_dev
>>>> + * structure. This would be relevant in cases where the startup delay
>>>> + * is in the range of milliseconds.
>>>> + */
>>>> + usleep_range(CC2_STARTUP_TIME_US, CC2_STARTUP_TIME_US + 125);
>
>>> Note that the regulator startup delay is the time taken for the
>>> regulator to power up so if the device needs additional delay then that
>>> will always need to be in addition to whatever the regulator is doing.
>
>> What I mean by that is that the device cannot be ready until the
>> regulator powers it up (obvious) plus the start up time of the device
>> itself once it gets powered up. So if a regulator takes for example 1 ms
>> to power up, the sleep function could (and should) wait for 1 ms longer.
>
> No, the sleep function should do nothing of the sort - if any delay is
> neeeded for the regulator it will be handled as part of enabling the
> regulator. This is not exposed to client drivers because it is
> transparent to them.
That sounds great. Then there is no need for the comment altogether and
the TODO will go away.
Thank you again and best regards,
Javier Carrrasco
