[PATCH 3/7] drm/panel: sitronix-st7789v: Specify the expected bus format

[Maxime Ripard]

Hi,

On Fri, Jun 09, 2023 at 04:59:47PM +0200, Miquel Raynal wrote:
> The LCD controller supports RGB444, RGB565 and RGB888. The value that is
> written in the COLMOD register indicates using RGB888, so let's clearly
> specify the in-use bus format.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>
> ---
>  drivers/gpu/drm/panel/panel-sitronix-st7789v.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panel/panel-sitronix-st7789v.c b/drivers/gpu/drm/panel/panel-sitronix-st7789v.c
> index e9ca7ebb458a..0abb45bea18d 100644
> --- a/drivers/gpu/drm/panel/panel-sitronix-st7789v.c
> +++ b/drivers/gpu/drm/panel/panel-sitronix-st7789v.c
> @@ -6,6 +6,7 @@
>  #include <linux/delay.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/module.h>
> +#include <linux/media-bus-format.h>
>  #include <linux/regulator/consumer.h>
>  #include <linux/spi/spi.h>
>  
> @@ -170,6 +171,7 @@ static int st7789v_get_modes(struct drm_panel *panel,
>  			     struct drm_connector *connector)
>  {
>  	struct drm_display_mode *mode;
> +	u32 bus_format = MEDIA_BUS_FMT_RGB666_1X18;

I'm not sure it should be set in stone in the driver.

This is a property of the panel/controller, but also one of the RGB
controller upstream that will and how the board has been wired.

It's not unusual for boards with a limited number of GPIOs to take a
RGB888 panel and connect only as a RGB565 with the lowest bits to the
ground for example.

So I think this should come from the device tree, ideally from the media
graph endpoint.

Maxime