Re: [PATCH v2 1/2] fbdev: Split frame buffer support in FB and FB_CORE symbols

From: Javier Martinez Canillas
Date: Mon Jul 03 2023 - 03:47:38 EST


Thomas Zimmermann <tzimmermann@xxxxxxx> writes:

Hello Thomas,

Thanks for your review.

> Hi
>
> Am 01.07.23 um 23:44 schrieb Javier Martinez Canillas:

[...]

>>
>> +menuconfig FB_CORE
>> + tristate "Core support for frame buffer devices"
>
> With the text, this is visible; as others noted.
>

Yes, I misremembered what made a Kconfig symbol non-visible, and thought
that was just the lack of a help section but forgot to remove the prompt.

This is already fixed in v3.

>> +
>> menuconfig FB
>> - tristate "Support for frame buffer devices"
>> + tristate "Support for frame buffer device drivers"
>
> Just keep the text as-is.
>

I disagree. Because we are slightly changing the Kconfig symbol semantics
here, for instance CONFIG_FB_CORE + CONFIG_DRM_FBDEV_EMULATION will also
provide a frame buffer device (and with CONFIG_FB_DEVICE, will be exposed
to user-space as a /dev/fb? device).

So now CONFIG_FB is really about allowing the native fbdev drivers to be
enabled. That's why I'm changing the prompt text to make that more clear.

[...]

>> config FB_DEVICE
>> bool "Provide legacy /dev/fb* device"
>> - depends on FB
>> + select FB_CORE
>
> This should depend on FB_CORE.
>

Yes, already fixed in v3 too. I did a select to prevent symbol circular
dependencies but doing that lead to CONFIG_FB_CORE=y even if CONFIG_DRM
was set as a module.

But with the "select FB_CORE if DRM_FBDEV_EMULATION" in the DRM symbol as
Arnd suggested, I was able to have FB_DEVICE to depend on FB_CORE again.

> Best regards
> Thomas
>

--
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat