Re: [PATCH v2 6/7] platform: x86: Add intel_skl_int3472 driver

[Andy Shevchenko]

On Tue, Jan 19, 2021 at 12:11:40AM +0000, Daniel Scally wrote:
> On 18/01/2021 21:19, Daniel Scally wrote:

> I'm more and more confident that this will work, but it has some
> knock-on effects:
> 
> The both clk and regulator gpio driver expects to be able to fetch the
> GPIO using devm_gpiod_get(&pdev->dev, "enable", ...). That won't work of
> course, so we need to add another GPIO lookup table so those drivers can
> see the GPIOs. For that, we need to know what dev_name(&pdev->dev) will
> be so we can set the .dev_id member of a gpiod_lookup_table to that
> value, but that isn't set until _after_ the pdev is registered (because
> it has to figure out the id, we can't manually set the IDs because there
> could be more than one instance of int3472-discrete bound to multiple
> PMIC devices, and we don't know which id the current one should have).
> Finally, we can't wait until the device is registered because it
> immediately probes, can't find the GPIO and then fails probe.
> 
> It's similar problem that causes us to need the i2c-acpi name format
> macros, but complicated by the dynamic ID part of dev_name(&pdev->dev)
> 
> Solving it is a bit of a sticky one; perhaps something like moving the
> dev_set_name() part of platform_device_add() [1] to its own function,
> that's called in both platform_device_alloc() and
> platform_device_register(). That way it would be available before the
> device itself was registered, meaning we could create the lookup table
> before it probes the driver.

See my previous reply. TL;DR: you have to modify clk-gpio.c to export couple of
methods to be able to use it as a library.

> (also, Laurent, if we did it this way we wouldn't be able to also handle
> the led-indicator GPIO here without some fairly major rework)

LED indicators are done as LED class devices (see plenty of examples in PDx86
drivers: drivers/platform/x86/)

-- 
With Best Regards,
Andy Shevchenko