linux-kernel - Re: [RFT PATCH 2/4] platform/x86: int3472: led: don't use gpiod_toggle_active

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Message-ID: <2b5db794-c00f-e9f5-c0c9-4c5fb4df0802@redhat.com>
Date:   Wed, 27 Sep 2023 11:40:40 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Daniel Scally <djrscally@...il.com>,
        Mark Gross <markgross@...nel.org>
Cc:     linux-gpio@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [RFT PATCH 2/4] platform/x86: int3472: led: don't use
 gpiod_toggle_active_low()

Hi,

On 9/26/23 16:59, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.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@...aro.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.

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));