diff mbox series

drm: fix up fbdev Kconfig defaults

Message ID 20230911205338.2385278-1-arnd@kernel.org
State New
Headers
Series drm: fix up fbdev Kconfig defaults |

Commit Message

Arnd Bergmann Sept. 11, 2023, 8:52 p.m. UTC 
  From: Arnd Bergmann <arnd@arndb.de>

As a result of the recent Kconfig reworks, the default settings for the
framebuffer interfaces changed in unexpected ways:

Configurations that leave CONFIG_FB disabled but use DRM now get
DRM_FBDEV_EMULATION by default. This also turns on the deprecated /dev/fb
device nodes for machines that don't actually want it.

In turn, configurations that previously had DRM_FBDEV_EMULATION enabled
now only get the /dev/fb front-end but not the more useful framebuffer
console, which is not selected any more.

We had previously decided that any combination of the three frontends
(FB_DEVICE, FRAMEBUFFER_CONSOLE and LOGO) should be selectable, but the
new default settings mean that a lot of defconfig files would have to
get adapted.

Change the defaults back to what they were in Linux 6.5:

 - Leave DRM_FBDEV_EMULATION turned off unless CONFIG_FB
   is enabled. Previously this was a hard dependency but now the two are
   independent. However, configurations that enable CONFIG_FB probably
   also want to keep the emulation for DRM, while those without FB
   presumably did that intentionally in the past.

 - Leave FB_DEVICE turned off for FB=n. Following the same
   logic, the deprecated option should not automatically get enabled
   here, most users that had FB turned off in the past do not want it,
   even if they want the console

 - Turn the FRAMEBUFFER_CONSOLE option on if
   DRM_FBDEV_EMULATION is set to avoid having to change defconfig
   files that relied on it being selected unconditionally in the past.
   This also makes sense since both LOGO and FB_DEVICE are now disabled
   by default for builds without CONFIG_FB, but DRM_FBDEV_EMULATION
   would make no sense if all three are disabled.

Fixes: a5ae331edb02b ("drm: Drop select FRAMEBUFFER_CONSOLE for DRM_FBDEV_EMULATION")
Fixes: 701d2054fa317 ("fbdev: Make support for userspace interfaces configurable")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/gpu/drm/Kconfig          | 2 +-
 drivers/video/console/Kconfig    | 1 +
 drivers/video/fbdev/core/Kconfig | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

Comments

Arnd Bergmann Sept. 12, 2023, 7:39 a.m. UTC | #1 
On Tue, Sep 12, 2023, at 09:14, Geert Uytterhoeven wrote:
> On Mon, Sep 11, 2023 at 10:53 PM Arnd Bergmann <arnd@kernel.org> wrote:
>> --- 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.

I think it still makes some sense though, as configs that have
both DRM and FB enabled almost certainly want this enabled.

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

Correct, this should restore the console on configs that
accidentally lost it. The real problem here is much older,
the assymetry between framebuffer-only configs (with console
default off) and DRM configs (with console selected
unconditionally) started back in 2009 with commit 6fcefd56f5060
("drm/kms: fix kms helper license + Kconfig").

I think that was a mistake, but there is little we can do
to fix that now without breaking users.

The only alternative I can think of would be to default-enable
or force-enable FRAMEBUFFER_CONSOLE for any config that includes
both VT_CONSOLE and FB_CORE. This would increase defconfig
builds for systems that currently only want CONFIG_FB for
either FB_DEVICE or LOGO but don't care about
FRAMEBUFFER_CONSOLE. I have no idea who uses such a config,
but I think Javier previously said this was an important
use case.

>> 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.

How? FB_DEVICE is a new config that was just split out from
CONFIG_FB in 6.6-rc1, so nobody should have any defconfig
that disables CONFIG_FB but relies on the FB_DEVICE default yet.

    Arnd
Javier Martinez Canillas Sept. 12, 2023, 7:48 a.m. UTC | #2 
Geert Uytterhoeven <geert@linux-m68k.org> writes:

Hello Geert,

> Hi Arnd,
>
> On Mon, Sep 11, 2023 at 10:53 PM Arnd Bergmann <arnd@kernel.org> wrote:

[...]

>> --- 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) ?

>>         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").
>
>>         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'.
Javier Martinez Canillas Sept. 12, 2023, 7:55 a.m. UTC | #3 
"Arnd Bergmann" <arnd@arndb.de> writes:

> On Tue, Sep 12, 2023, at 09:14, Geert Uytterhoeven wrote:
>> On Mon, Sep 11, 2023 at 10:53 PM Arnd Bergmann <arnd@kernel.org> wrote:

[...]

>
> The only alternative I can think of would be to default-enable
> or force-enable FRAMEBUFFER_CONSOLE for any config that includes
> both VT_CONSOLE and FB_CORE. This would increase defconfig
> builds for systems that currently only want CONFIG_FB for
> either FB_DEVICE or LOGO but don't care about
> FRAMEBUFFER_CONSOLE. I have no idea who uses such a config,
> but I think Javier previously said this was an important
> use case.
>

Yes, IMO that should be a possible combination.

>>> 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.
>
> How? FB_DEVICE is a new config that was just split out from
> CONFIG_FB in 6.6-rc1, so nobody should have any defconfig
> that disables CONFIG_FB but relies on the FB_DEVICE default yet.
>

Ah, scratch my previous comment about making this default 'y' then. For
some reasons I thought that FB_DEVICE was added in v6.5 but see now that
commit 701d2054fa31 ("fbdev: Make support for userspace interfaces
configurable") landed in v6.6-rc1:

$ git tag --contains 701d2054fa31 | tail -1
v6.6-rc1
Arnd Bergmann Sept. 12, 2023, 7:58 a.m. UTC | #4 
On Tue, Sep 12, 2023, at 09:48, Javier Martinez Canillas wrote:
> Geert Uytterhoeven <geert@linux-m68k.org> writes:
>> On Mon, Sep 11, 2023 at 10:53 PM Arnd Bergmann <arnd@kernel.org> wrote:
>>> --- 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) ?

That wouldn't work unless we swap around the 'select DRM_CORE',
which currently gets selected when DRM_FBDEV_EMULATION is
turned on.

>>>         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) ?

That would be the same as a plain 'default y' based on the
dependencies. We can definitely do that, but it does change
the behavior for FB-only users.

At the moment, we have 21 defconfig files in the kernel
that enable CONFIG_FB but not CONFIG_FRAMEBUFFER_CONSOLE:

$ git grep -l CONFIG_FB=y  arch/*configs/ | xargs grep -L "FRAMEBUFFER_CONSOLE=\|DRM="
arch/arm/configs/am200epdkit_defconfig
arch/arm/configs/assabet_defconfig
arch/arm/configs/clps711x_defconfig
arch/arm/configs/ep93xx_defconfig
arch/arm/configs/footbridge_defconfig
arch/arm/configs/h3600_defconfig
arch/arm/configs/multi_v4t_defconfig
arch/arm/configs/mvebu_v5_defconfig
arch/arm/configs/pxa910_defconfig
arch/arm/configs/s3c6400_defconfig
arch/arm/configs/wpcm450_defconfig
arch/microblaze/configs/mmu_defconfig
arch/mips/configs/cobalt_defconfig
arch/mips/configs/generic/board-ranchu.config
arch/mips/configs/malta_qemu_32r6_defconfig
arch/mips/configs/maltaaprp_defconfig
arch/mips/configs/maltasmvp_defconfig
arch/mips/configs/maltasmvp_eva_defconfig
arch/mips/configs/maltaup_defconfig
arch/sh/configs/r7785rp_defconfig
arch/sh/configs/se7343_defconfig

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

I really don't want to start enabling this for configs that
didn't have it in the past.

    Arnd
Thomas Zimmermann Sept. 12, 2023, 8:11 a.m. UTC | #5 
Hi

Am 12.09.23 um 09:14 schrieb Geert Uytterhoeven:
[...]
>> --- 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.

Would it make sense to make FRAMEBUFFER_CONSOLE an independent option 
and have FBDEV_EMULATION depend on it? Something like this:

FRAMEBUFFER_CONSOLE
	depends on DRM || FB
	select FB_CORE

FBDEV_EMULATION
	depends on DRM
	depends on FRAMEBUFFER_CONSOLE
	default y

So if any graphics subsystems are enabled, FRAMEBUFFER_CONSOLE is 
select-able. But for DRM, FBDEV_EMULATION disables the console. That 
option remains more for historical reasons than actual usefulness.

Best regards
Thomas

> 
>>          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?).
> So this is the fix for commit a5ae331edb02b ("drm: Drop select
> FRAMEBUFFER_CONSOLE for DRM_FBDEV_EMULATION").
> 
>>          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.
> 
>>          help
>>            Say Y here if you want the legacy /dev/fb* device file and
>>            interfaces within sysfs anc procfs. It is only required if you
> 
> Gr{oetje,eeting}s,
> 
>                          Geert
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
Arnd Bergmann Sept. 12, 2023, 9:04 a.m. UTC | #6 
On Tue, Sep 12, 2023, at 04:18, Geert Uytterhoeven wrote:
> On Tue, Sep 12, 2023 at 10:11 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>> Am 12.09.23 um 09:14 schrieb Geert Uytterhoeven:
>> [...]
>> >> --- 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.
>>
>> Would it make sense to make FRAMEBUFFER_CONSOLE an independent option
>> and have FBDEV_EMULATION depend on it? Something like this:
>>
>> FRAMEBUFFER_CONSOLE
>>         depends on DRM || FB
>>         select FB_CORE
>>
>> FBDEV_EMULATION
>>         depends on DRM
>>         depends on FRAMEBUFFER_CONSOLE
>>         default y
>
> Oops, now you can no longer have FBDEV_EMULATION without
> FRAMEBUFFER_CONSOLE, which is useful to be able to enable
> FB_DEVICE...
>
> And what's the point (if DRM is enabled) of having FB_CORE with
> FBDEV_EMULATION disabled?

I think we technically have the choice between selecting FB_CORE from
all the providers (FB and DRM_FBDEV_EMULATION) or from all the
consumers (FRAMEBUFFER_CONSOLE, FB_DEVICE and LOGO). We chose
to have it the former way at the moment, and I think what Thomas
suggests here is to change it to the latter.

The downside of the current approach is that you can have
pointless configuration with

CONFIG_FB=y
CONFIG_DRM=y
CONFIG_DRM_FBDEV_EMULATION=y
CONFIG_FRAMEBUFFER_CONSOLE=n
CONFIG_FB_DEVICE=n
CONFIG_LOGO=n

where the fb_core module gets initialized but it is impossible
for anything to draw on it.

Another option we have would be to try to separate the Kconfig
options for DRM and FB a little further, in anticipation of
reducing the amount of shared code in the long run (a lot of
FB code is built but never used when enabling console on
DRM).

So adding a new

config DRM_CONSOLE
     bool "enable console on DRM devices"
     depends on DRM
     depends on VT_CONSOLE
     depends on !UML
     select FB_CORE
     select FRAMEBUFFER_CONSOLE_CORE # new helper sym
     select FRAMEBUFFER_CONSOLE_DETECT_PRIMARY
     default y

would give us a path to minimize the shared code
further, allowing the console code to be reused as
before, but without having to pull in the code that
is now only needed for FB_DEVICE. In this scenario,
we'd still have CONFIG_DRM_FBDEV_EMULATION like

config DRM_FBDEV_EMULATION
      bool "full emulation of fbdev layer for DRM"
      select FB_CORE
      select FB_DEVICE
      default FB # if enabled already, use it

but only use that if we actually want FB_DEVICE.

      Arnd
Thomas Zimmermann Sept. 18, 2023, 7:25 a.m. UTC | #7 
Hi

Am 11.09.23 um 22:52 schrieb Arnd Bergmann:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> As a result of the recent Kconfig reworks, the default settings for the
> framebuffer interfaces changed in unexpected ways:
> 
> Configurations that leave CONFIG_FB disabled but use DRM now get
> DRM_FBDEV_EMULATION by default. This also turns on the deprecated /dev/fb
> device nodes for machines that don't actually want it.
> 
> In turn, configurations that previously had DRM_FBDEV_EMULATION enabled
> now only get the /dev/fb front-end but not the more useful framebuffer
> console, which is not selected any more.
> 
> We had previously decided that any combination of the three frontends
> (FB_DEVICE, FRAMEBUFFER_CONSOLE and LOGO) should be selectable, but the
> new default settings mean that a lot of defconfig files would have to
> get adapted.
> 
> Change the defaults back to what they were in Linux 6.5:
> 
>   - Leave DRM_FBDEV_EMULATION turned off unless CONFIG_FB
>     is enabled. Previously this was a hard dependency but now the two are
>     independent. However, configurations that enable CONFIG_FB probably
>     also want to keep the emulation for DRM, while those without FB
>     presumably did that intentionally in the past.
> 
>   - Leave FB_DEVICE turned off for FB=n. Following the same
>     logic, the deprecated option should not automatically get enabled
>     here, most users that had FB turned off in the past do not want it,
>     even if they want the console
> 
>   - Turn the FRAMEBUFFER_CONSOLE option on if
>     DRM_FBDEV_EMULATION is set to avoid having to change defconfig
>     files that relied on it being selected unconditionally in the past.
>     This also makes sense since both LOGO and FB_DEVICE are now disabled
>     by default for builds without CONFIG_FB, but DRM_FBDEV_EMULATION
>     would make no sense if all three are disabled.
> 
> Fixes: a5ae331edb02b ("drm: Drop select FRAMEBUFFER_CONSOLE for DRM_FBDEV_EMULATION")
> Fixes: 701d2054fa317 ("fbdev: Make support for userspace interfaces configurable")
> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>

> ---
>   drivers/gpu/drm/Kconfig          | 2 +-
>   drivers/video/console/Kconfig    | 1 +
>   drivers/video/fbdev/core/Kconfig | 2 +-
>   3 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 7df8b6875b121..144a9a1d31cea 100644
> --- 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
>   	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
>   	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
>   	help
>   	  Say Y here if you want the legacy /dev/fb* device file and
>   	  interfaces within sysfs anc procfs. It is only required if you

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
Javier Martinez Canillas Sept. 18, 2023, 8:57 a.m. UTC | #8 
Thomas Zimmermann <tzimmermann@suse.de> writes:

> Hi
>
> Am 11.09.23 um 22:52 schrieb Arnd Bergmann:
>> From: Arnd Bergmann <arnd@arndb.de>
>> 
>> As a result of the recent Kconfig reworks, the default settings for the
>> framebuffer interfaces changed in unexpected ways:
>> 
>> Configurations that leave CONFIG_FB disabled but use DRM now get
>> DRM_FBDEV_EMULATION by default. This also turns on the deprecated /dev/fb
>> device nodes for machines that don't actually want it.
>> 
>> In turn, configurations that previously had DRM_FBDEV_EMULATION enabled
>> now only get the /dev/fb front-end but not the more useful framebuffer
>> console, which is not selected any more.
>> 
>> We had previously decided that any combination of the three frontends
>> (FB_DEVICE, FRAMEBUFFER_CONSOLE and LOGO) should be selectable, but the
>> new default settings mean that a lot of defconfig files would have to
>> get adapted.
>> 
>> Change the defaults back to what they were in Linux 6.5:
>> 
>>   - Leave DRM_FBDEV_EMULATION turned off unless CONFIG_FB
>>     is enabled. Previously this was a hard dependency but now the two are
>>     independent. However, configurations that enable CONFIG_FB probably
>>     also want to keep the emulation for DRM, while those without FB
>>     presumably did that intentionally in the past.
>> 
>>   - Leave FB_DEVICE turned off for FB=n. Following the same
>>     logic, the deprecated option should not automatically get enabled
>>     here, most users that had FB turned off in the past do not want it,
>>     even if they want the console
>> 
>>   - Turn the FRAMEBUFFER_CONSOLE option on if
>>     DRM_FBDEV_EMULATION is set to avoid having to change defconfig
>>     files that relied on it being selected unconditionally in the past.
>>     This also makes sense since both LOGO and FB_DEVICE are now disabled
>>     by default for builds without CONFIG_FB, but DRM_FBDEV_EMULATION
>>     would make no sense if all three are disabled.
>> 
>> Fixes: a5ae331edb02b ("drm: Drop select FRAMEBUFFER_CONSOLE for DRM_FBDEV_EMULATION")
>> Fixes: 701d2054fa317 ("fbdev: Make support for userspace interfaces configurable")
>> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>
> Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
>

Pushed to drm-misc (drm-misc-fixes). Thanks!
diff mbox series

Patch

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 7df8b6875b121..144a9a1d31cea 100644
--- 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
 	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
 	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
 	help
 	  Say Y here if you want the legacy /dev/fb* device file and
 	  interfaces within sysfs anc procfs. It is only required if you