Re: [PATCH 2/2] sunxi: video: Add support for active low LCD power pin

[Andre Przywara <andre.przywara@arm.com>]

On Tue, 22 Nov 2022 21:57:03 +0100
Giulio Benetti <giulio.benetti@benettiengineering.com> wrote:

Hi,

> On some board gpio to power LCD can be active low, so let's add
> CONFIG_VIDEO_LCD_POWER_ACTIVE_LOW to allow this.

This is all so very sadly outdated code, which could be all solved
very nicely by just looking at the DT.
Do you describe the backlight in the DT, for Linux, by any chance?
Can we at least try to read that information from there, instead of
adding Kconfig parameters for every variation?

> Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
> ---
>  arch/arm/mach-sunxi/Kconfig         | 7 +++++++
>  drivers/video/sunxi/sunxi_display.c | 4 ++++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/arch/arm/mach-sunxi/Kconfig b/arch/arm/mach-sunxi/Kconfig
> index dbe6005daa..a7375b53a6 100644
> --- a/arch/arm/mach-sunxi/Kconfig
> +++ b/arch/arm/mach-sunxi/Kconfig
> @@ -867,6 +867,13 @@ config VIDEO_LCD_POWER
>  	Set the power enable pin for the LCD panel. This takes a string in the
>  	format understood by sunxi_name_to_gpio, e.g. PH1 for pin 1 of port H.
>  
> +config VIDEO_LCD_POWER_ACTIVE_LOW
> +	bool "LCD panel power enable pin is inverted"
> +	depends on VIDEO_SUNXI
> +	default n
> +	---help---
> +	Set this if the lcd power pin is active low.
> +
>  config VIDEO_LCD_RESET
>  	string "LCD panel reset pin"
>  	depends on VIDEO_SUNXI
> diff --git a/drivers/video/sunxi/sunxi_display.c b/drivers/video/sunxi/sunxi_display.c
> index 2ee6212c58..12b542d65b 100644
> --- a/drivers/video/sunxi/sunxi_display.c
> +++ b/drivers/video/sunxi/sunxi_display.c
> @@ -588,7 +588,11 @@ static void sunxi_lcdc_panel_enable(void)
>  	pin = sunxi_name_to_gpio(CONFIG_VIDEO_LCD_POWER);
>  	if (pin >= 0) {
>  		gpio_request(pin, "lcd_power");
> +#ifdef CONFIG_VIDEO_LCD_POWER_ACTIVE_LOW

At the very least that should be using IS_ENABLED() and proper C code.

Cheers,
Andre

> +		gpio_direction_output(pin, 0);
> +#else
>  		gpio_direction_output(pin, 1);
> +#endif
>  	}
>  
>  	if (reset_pin >= 0)