[PATCH v2 02/25] drm/panel: add backlight support

[Linus Walleij]

On Sat, Dec 7, 2019 at 3:04 PM Sam Ravnborg <sam at ravnborg.org> wrote:

> Panels often supports backlight as specified in a device tree.
> Update the drm_panel infrastructure to support this to
> simplify the drivers.
>
> With this the panel driver just needs to add the following to the
> probe() function:
>
>     err = drm_panel_of_backlight(panel);
>     if (err)
>             return err;
>
> Then drm_panel will handle all the rest.
>
> There is one caveat with the backlight support.
> If drm_panel_(enable|disable) are called multiple times
> in row then backlight_(enable|disable) will be called multiple times.
>
> The above will happen when a panel drivers unconditionally
> calls drm_panel_disable() in their shutdown() function,
> whan the panel is already disabled and then shutdown() is called.
>
> Reading the backlight code it seems safe to call
> the backlight_(enable|disable) several times.
>
> v3:

v3 looks good to me +/- Laurent's comments:
Reviewed-by: Linus Walleij <linus.walleij at linaro.org>

Yours,
Linus Walleij