Re: [PATCH 18/18] ipu3: Add driver for dummy INT3472 ACPI device

[Daniel Scally <djrscally@xxxxxxxxx>]

On 01/12/2020 18:49, Andy Shevchenko wrote:
>>>> +	table_entry = (struct gpiod_lookup)GPIO_LOOKUP_IDX(acpi_dev_name(adev),
>>>> +							   ares->data.gpio.pin_table[0],
>>>> +							   func, 0, GPIO_ACTIVE_HIGH);
>>>
>>> You won't need this if you have regular INT3472 platform driver.
>>> Simple call there _DSM to map resources to the type and use devm_gpiod_get on
>>> consumer behalf. Thus, previous patch is not needed.
>>
>> How does the consumer (the camera sensor) retrieve the GPIO though ? The
>> _DSM is in the PMIC device object, while the real consumer is the camera
>> sensor.
> 
> 1. A GPIO proxy
> 2. A custom GPIO lookup tables
> 3. An fwnode passing to the sensor (via swnodes graph)
> 
> First may issue deferred probe, while second needs some ordering tricks I guess.
> Third one should also provide an ACPI GPIO mapping table or so to make the
> consumer rely on names rather than custom numbers.
> 
> Perhaps someone may propose other solutions.

Hi Andy

Sorry; some more clarification here if you have time please:

1. Do you mean here, register a new gpio_chip providing GPIOs to the
sensors, and just have the .set() callback for that function set the
corresponding line against the INT3472 device?
2. I thought custom GPIO lookup tables was what I was doing, are you
referring to something else?
3. I guess you mean something like of_find_gpio() and acpi_find_gpio()
here? As far as I can see there isn't currently a swnodes
equivalent...we could just pass it via reference of course but it would
mean the sensor drivers would all need to account for that.