Re: [PATCH] drm: fix up fbdev Kconfig defaults

Geert Uytterhoeven [off-list ref] writes:

Hello Geert,

Hi Arnd,

On Mon, Sep 11, 2023 at 10:53 PM Arnd Bergmann [off-list ref] wrote:

[...]

quoted

--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig

@@ -135,7 +135,7 @@ config DRM_FBDEV_EMULATION
        bool "Enable legacy fbdev support for your modesetting driver"
        depends on DRM
        select FRAMEBUFFER_CONSOLE_DETECT_PRIMARY if FRAMEBUFFER_CONSOLE
-       default y
+       default FB

While this is true for existing configs, it is no longer true in general,
as DRM_FBDEV_EMULATION is no longer related to FB.

Maybe default y if (FB_DEVICE || FRAMEBUFFER_CONSOLE) ?

quoted

        help
          Choose this option if you have a need for the legacy fbdev
          support. Note that this support also provides the linux console

diff --git a/drivers/video/console/Kconfig b/drivers/video/console/Kconfig
index b575cf54174af..83c2d7329ca58 100644
--- a/drivers/video/console/Kconfig
+++ b/drivers/video/console/Kconfig

@@ -74,6 +74,7 @@ config DUMMY_CONSOLE_ROWS
 config FRAMEBUFFER_CONSOLE
        bool "Framebuffer Console support"
        depends on FB_CORE && !UML
+       default DRM_FBDEV_EMULATION

Sounds good to me, although it looks a bit strange at first sight
(FRAMEBUFFER_CONSOLE defaults to n on a system with real fbdev, but
y on emulated fbdev?).

And there Maybe default y if (FB || DRM_FBDEV_EMULATION) ?

So this is the fix for commit a5ae331edb02b ("drm: Drop select
FRAMEBUFFER_CONSOLE for DRM_FBDEV_EMULATION").

quoted

        select VT_HW_CONSOLE_BINDING
        select CRC32
        select FONT_SUPPORT

diff --git a/drivers/video/fbdev/core/Kconfig b/drivers/video/fbdev/core/Kconfig
index 114cb8aa6c8fd..804c2bec9b43c 100644
--- a/drivers/video/fbdev/core/Kconfig
+++ b/drivers/video/fbdev/core/Kconfig

@@ -28,7 +28,7 @@ config FIRMWARE_EDID
 config FB_DEVICE
        bool "Provide legacy /dev/fb* device"
        depends on FB_CORE
-       default y
+       default FB

Changing this means possibly causing regressions on systems running
an fbdev userspace.

Right, specially if using DRM fbdev emulation since then the default will
be different between v6.5 and v6.6 (that's what this patch tries to avoid).

So probably we could keept that default as 'y'.

-- 
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat