[PATCH] Ask a question about why can't use GPIOAO: GPIO_TEST_N

[Neil Armstrong]

Hi,

On 14/07/2022 04:07, Zhang Ning wrote:
> first this is not a code review, just ask a question.
> 
> I started to enable MagicBox M16S, and sent patches for review.
> 
> but leds are not enabled.
> 
> I have tried, and found gpioao: GPIO_TEST_N can control led on off.
> 
> thus I add it to dts:
> 
>          leds {
>                  compatible = "gpio-leds";
> 
>                  led-white {
>                          color = <LED_COLOR_ID_WHITE>;
>                          function = LED_FUNCTION_POWER;
>                          gpios = <&gpio_ao GPIO_TEST_N GPIO_ACTIVE_HIGH>;
>                          default-state = "keep";
>                  };
>          };
> 
> but failed with error -22.
> 
> and simply change GPIO_TEST_N to GPIOAO_2, no error.
> 
> thus find pinctrl driver doesn't allow to use this gpio.
> 
> why?

The TEST_N pinctrl needs a SMC call to set the pin GPIO direction, so it needs
more code to control the pin.

I did an experimental support a few years ago:
https://github.com/superna9999/linux/commits/amlogic/v4.19/gpio-test-n

I would need to be refreshed to work on 5.20.

Neil

> 
> Signed-off-by: Zhang Ning <zhangn1985 at qq.com>
> ---
>   drivers/pinctrl/meson/pinctrl-meson-gxl.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pinctrl/meson/pinctrl-meson-gxl.c b/drivers/pinctrl/meson/pinctrl-meson-gxl.c
> index 51408996255b..fb5fa88b30c7 100644
> --- a/drivers/pinctrl/meson/pinctrl-meson-gxl.c
> +++ b/drivers/pinctrl/meson/pinctrl-meson-gxl.c
> @@ -820,7 +820,7 @@ static struct meson_bank meson_gxl_periphs_banks[] = {
>   
>   static struct meson_bank meson_gxl_aobus_banks[] = {
>   	/*   name    first      last      irq	pullen  pull    dir     out     in  */
> -	BANK("AO",   GPIOAO_0,  GPIOAO_9, 0, 9, 0,  16, 0, 0,   0,  0,  0, 16,  1,  0),
> +	BANK("AO",   GPIOAO_0,  GPIO_TEST_N, 0, 9, 0,  16, 0, 0,   0,  0,  0, 16,  1,  0),
>   };
>   
>   static struct meson_pinctrl_data meson_gxl_periphs_pinctrl_data = {