Re: [PATCH 1/2] fbdev: Split frame buffer support in FB and FB_CORE symbols

Arnd Bergmann
2023-06-30T11:38:35Z

On Fri, Jun 30, 2023, at 12:51, Javier Martinez Canillas wrote:
> "Arnd Bergmann" <arnd@arndb.de> writes:
>
>>> @@ -59,7 +71,7 @@ config FIRMWARE_EDID
>>>
>>> config FB_DEVICE
>>> bool "Provide legacy /dev/fb* device"
>>> - depends on FB
>>> + depends on FB_CORE
>>> default y
>>> help
>>> Say Y here if you want the legacy /dev/fb* device file and
>>
>> I don't see this symbol in linux-next yet, what tree are you using
>> as a base?
>>
>
> It's now in the drm-misc/drm-misc-next branch [1]. It's not in -next yet
> because it just landed a few days ago [2].
>
> [1]: https://cgit.freedesktop.org/drm/drm-misc/log/?h=drm-misc-next
> [2]: https://cgit.freedesktop.org/drm/drm-misc/commit/?id=701d2054fa3
>
> In fact, that's the reason why I rebased my previous attempt [0].

Ok.

I wonder if it would make sense to also make FB_DEVICE depend on FB
instead of FB_CORE then. I don't think there is any actual dependency
between the two, but as I understand we want modern distros to use
neither FB nor FB_DEVICE, so tying them together with a dependency
may be desirable anyway.

>>> config FB_BACKLIGHT
>>> tristate
>>> - depends on FB
>>> + depends on FB_CORE
>>> select BACKLIGHT_CLASS_DEVICE
>>
>> Separating this one from FB_CORE would help avoid circular dependencies,
>> this one keeps causing issues.
>>
>
> You mean separating from FB or should I keep the existing depends on FB?
>
> It seems this is only used by fbdev drivers so probably the latter?

Right, I meant keeping the dependency on FB. Ideally we'd
turn this all into a set of 'depends on' instead of 'select',
but that is a completely separate topic.

Arnd