Re: [PATCH v2] drivers/firmware: fix SYSFB depends to prevent build failures

[Javier Martinez Canillas <javierm@redhat.com>]

Hello Geert,

On 7/27/21 12:03 PM, Geert Uytterhoeven wrote:

[snip]

> Thanks for your patch!
>

You are welcome.

>> --- a/drivers/firmware/Kconfig
>> +++ b/drivers/firmware/Kconfig
>> @@ -254,7 +254,7 @@ config QCOM_SCM_DOWNLOAD_MODE_DEFAULT
>>  config SYSFB
>>         bool
>>         default y
>> -       depends on X86 || ARM || ARM64 || RISCV || COMPILE_TEST
>> +       depends on X86 || EFI
> 
> Thanks, much better.
> Still, now this worm is crawling out of the X86 can, I'm wondering
> why this option is so important that it has to default to y?
> It is not just a dependency for SYSFB_SIMPLEFB, but also causes the
> inclusion of drivers/firmware/sysfb.c.
>

It defaults to yes because drivers/firmware/sysfb.c contains the logic
to register a "simple-framebuffer" device (or "efi-framebuffer" if the
CONFIG_SYSFB_SIMPLEFB Kconfig symbol is not enabled).

Not enabling this, would mean that a platform device to match a driver
supporting the EFI GOP framebuffer (e.g: simple{drm,fb} or efifb) will
not be registered. Which will lead to not having an early framebuffer.

The logic used to be in drivers/firmware/efi/efi-init.c, that's built
in if CONFIG_EFI is enabled. We just consolidated both X86 and EFI:

https://cgit.freedesktop.org/drm/drm-misc/commit/?id=8633ef82f101

Best regards,
-- 
Javier Martinez Canillas
Linux Engineering
Red Hat