Re: [PATCH v3 1/3] platform: x86: int3472: Add MFD cell for tps68470 LED

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Hi,

On 3/23/23 13:23, Lee Jones wrote:
> On Tue, 21 Mar 2023, Kate Hsuan wrote:
> 
>> Add MFD cell for tps68470-led.
>>
>> Reviewed-by: Daniel Scally <dan.scally@xxxxxxxxxxxxxxxx>
>> Signed-off-by: Kate Hsuan <hpa@xxxxxxxxxx>
>> ---
>>  drivers/platform/x86/intel/int3472/tps68470.c | 5 +++--
>>  1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/platform/x86/intel/int3472/tps68470.c b/drivers/platform/x86/intel/int3472/tps68470.c
>> index 5b8d1a9620a5..82ef022f8916 100644
>> --- a/drivers/platform/x86/intel/int3472/tps68470.c
>> +++ b/drivers/platform/x86/intel/int3472/tps68470.c
>> @@ -17,7 +17,7 @@
>>  #define DESIGNED_FOR_CHROMEOS		1
>>  #define DESIGNED_FOR_WINDOWS		2
>>
>> -#define TPS68470_WIN_MFD_CELL_COUNT	3
>> +#define TPS68470_WIN_MFD_CELL_COUNT	4
>>
>>  static const struct mfd_cell tps68470_cros[] = {
>>  	{ .name = "tps68470-gpio" },
>> @@ -193,7 +193,8 @@ static int skl_int3472_tps68470_probe(struct i2c_client *client)
>>  		cells[1].name = "tps68470-regulator";
>>  		cells[1].platform_data = (void *)board_data->tps68470_regulator_pdata;
>>  		cells[1].pdata_size = sizeof(struct tps68470_regulator_platform_data);
>> -		cells[2].name = "tps68470-gpio";
>> +		cells[2].name = "tps68470-led";
>> +		cells[3].name = "tps68470-gpio";
> 
> The question is, why is the MFD API being used out side of drivers/mfd?

Because Intel made a big mess about how they describe camera sensors + the matching clks / regulators / GPIOs and the optional PMIC in ACPI.

The drivers/platform/x86/intel/int3472/ code untangles this mess and in some cases it instantiates MFD cells (with a whole bunch of derived platform_data per cell) for a TPS68470 PMIC.

And sometimes while binding to an INT3472 ACPI device-node it does not instantiate any MFD cells at all since the INT3472 ACPI device-node does not always describe such a PMIC.

Oh and also depending on of the ACPI tables are targetting ChromeOS or Windows a different set of MFD cells needs to be instantiated. On ChromeOS most of the PMIC poking is done through ACPI through a ChomeOS specific custom ACPI OpRegion, so there there are only cells for GPIO and a driver providing the OpRegion are created.

So lots of ugly x86 platform specific handling, ACPI parsing, etc. which is why this landed under drivers/platform/x86/ . IIRC you were even involved in the original merge since there once was a much simpler MFD driver under driver/mfd which only supported the ChromeOS setup.

(but my memory may be deceiving me here).

Regards,

Hans





> 
>>  		for (i = 0; i < board_data->n_gpiod_lookups; i++)
>>  			gpiod_add_lookup_table(board_data->tps68470_gpio_lookup_tables[i]);
>> --
>> 2.39.2
>>
> 
> --
> Lee Jones [李琼斯]
> 




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