Re: [RFT PATCH 2/4] platform/x86: int3472: led: don't use gpiod_toggle_active_low()

Hans de Goede
2023-09-27T13:18:47Z

Hi Again,

On 9/27/23 15:08, Hans de Goede wrote:
> Hi Bart,
>
> On 9/27/23 12:44, Bartosz Golaszewski wrote:
>> On Wed, Sep 27, 2023 at 11:40 AM Hans de Goede <hdegoede@redhat.com> wrote:
>>>
>>> Hi,
>>>
>>> On 9/26/23 16:59, Bartosz Golaszewski wrote:
>>>> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>>>>
>>>> Instead of acpi_get_and_request_gpiod() + gpiod_toggle_active_low(), use
>>>> temporary lookup tables with appropriate lookup flags.
>>>>
>>>> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>>>> ---
>>>> drivers/platform/x86/intel/int3472/led.c | 12 ++++--------
>>>> 1 file changed, 4 insertions(+), 8 deletions(-)
>>>>
>>>> diff --git a/drivers/platform/x86/intel/int3472/led.c b/drivers/platform/x86/intel/int3472/led.c
>>>> index bca1ce7d0d0c..62e0cd5207a7 100644
>>>> --- a/drivers/platform/x86/intel/int3472/led.c
>>>> +++ b/drivers/platform/x86/intel/int3472/led.c
>>>> @@ -25,18 +25,14 @@ int skl_int3472_register_pled(struct int3472_discrete_device *int3472,
>>>> if (int3472->pled.classdev.dev)
>>>> return -EBUSY;
>>>>
>>>> - int3472->pled.gpio = acpi_get_and_request_gpiod(path, agpio->pin_table[0],
>>>> - "int3472,privacy-led");
>>>> + int3472->pled.gpio = skl_int3472_gpiod_get_from_temp_lookup(
>>>> + int3472->dev, path, agpio->pin_table[0],
>>>> + "int3472,privacy-led", polarity,
>>>> + GPIOD_OUT_LOW);
>>>
>>> Yeah so this is not going to work, path here is an ACPI device path, e.g.
>>> on my laptop (which actually uses the INT3472 glue code) the path-s of
>>> the 2 GPIO controllers are: `\_SB_.GPI0` resp `\_SB_.PC00.XHCI.RHUB.HS08.VGPO`
>>>
>>> Where as skl_int3472_gpiod_get_from_temp_lookup() stores the passed in path
>>> in gpiod_lookup_table.table[0].key, which is the dev_name() of the GPIO
>>> controller's parent dev which are `INTC1055:00` resp. `INTC1096:00` .
>>>
>>> So we are going to need to add some code to INT3472 to go from path to
>>> a correct value for gpiod_lookup_table.table[0].key which means partly
>>> reproducing most of acpi_get_gpiod:
>>>
>>> struct gpio_chip *chip;
>>> acpi_handle handle;
>>> acpi_status status;
>>>
>>> status = acpi_get_handle(NULL, path, &handle);
>>> if (ACPI_FAILURE(status))
>>> return ERR_PTR(-ENODEV);
>>>
>>> chip = gpiochip_find(handle, acpi_gpiochip_find);
>>> if (!chip)
>>> return ERR_PTR(-EPROBE_DEFER);
>>>
>>> And then get the key from the chip. Which means using gpiochip_find
>>> in the int3472 code now, which does not sound like an improvement.
>>>
>>> I think that was is needed instead is adding an active_low flag
>>> to acpi_get_and_request_gpiod() and then have that directly
>>> set the active-low flag on the returned desc.
>>>
>>
>> Ultimately I'd like everyone to use gpiod_get() for getting
>> descriptors but for now I get it's enough. Are you find with this
>> being done in a single patch across GPIO and this driver?
>
> Yes doing this in a single patch is fine.
>
> Also I'm fine with merging such a patch through the gpio tree .

So thinking about this more I realized that the int3472 code already
generates GPIO lookups for the sensor device for some
(powerdown, reset) GPIOs, it only needs the gpio_desc for
the case where the GPIO is turned into a regulator, clock or led.

Since the int3472 code is already generating lookups it already
has a way to go from path to a lookup "key":

status = acpi_get_handle(NULL, path, &handle);
if (ACPI_FAILURE(status))
return -EINVAL;

adev = acpi_fetch_acpi_dev(handle);
if (!adev)
return -ENODEV;

table_entry->key = acpi_dev_name(adev);

So we can get the key without needing to call gpio_find_chip()

So I do believe that the temp lookup approach should actually
work. I'm currently traveling, so no promises but I should
be able to rework your series in something which actually
works and which will:

1. Stop using gpiod_toggle_active_low()
2. Allow dropping acpi_get_and_request_gpiod()

So no need for a patch to add an active-low parameter to
acpi_get_and_request_gpiod(), sorry about the noise.

Regards,

Hans

>>>> if (IS_ERR(int3472->pled.gpio))
>>>> return dev_err_probe(int3472->dev, PTR_ERR(int3472->pled.gpio),
>>>> "getting privacy LED GPIO\n");
>>>>
>>>> - if (polarity == GPIO_ACTIVE_LOW)
>>>> - gpiod_toggle_active_low(int3472->pled.gpio);
>>>> -
>>>> - /* Ensure the pin is in output mode and non-active state */
>>>> - gpiod_direction_output(int3472->pled.gpio, 0);
>>>> -
>>>> /* Generate the name, replacing the ':' in the ACPI devname with '_' */
>>>> snprintf(int3472->pled.name, sizeof(int3472->pled.name),
>>>> "%s::privacy_led", acpi_dev_name(int3472->sensor));
>>>
>>