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Message-ID: <46d933f5-38e4-b46a-f94b-0e9a6e3b2e31@gmx.de>
Date:   Wed, 19 Jul 2023 19:37:41 +0200
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To:     Javier Martinez Canillas <javierm@redhat.com>,
        linux-kernel@vger.kernel.org
Cc:     Thomas Zimmermann <tzimmermann@suse.de>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Borislav Petkov <bp@alien8.de>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        David Airlie <airlied@gmail.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>,
        Jeffrey Hugo <quic_jhugo@quicinc.com>,
        Jingoo Han <jingoohan1@gmail.com>, Lee Jones <lee@kernel.org>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Nipun Gupta <nipun.gupta@amd.com>,
        Oded Gabbay <ogabbay@kernel.org>,
        Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        Sam Ravnborg <sam@ravnborg.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org,
        x86@kernel.org
References: <20230719081544.741051-1-javierm@redhat.com>
From:   Helge Deller <deller@gmx.de>
Subject: Re: [PATCH v6 0/4] Allow disabling all native fbdev drivers and only
 keeping DRM emulation
In-Reply-To: <20230719081544.741051-1-javierm@redhat.com>
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Precedence: bulk

Hi Javier,

On 7/19/23 10:15, Javier Martinez Canillas wrote:
> This patch series splits the fbdev core support in two different Kconfig
> symbols: FB and FB_CORE. The motivation for this is to allow CONFIG_FB t=
o
> be disabled, while still having the the core fbdev support needed for th=
e

One "the" too much.
(correcting just because this is a cover letter)

> CONFIG_DRM_FBDEV_EMULATION to be enabled. The motivation is automaticall=
y
> disabling all fbdev drivers instead of having to be disabled individuall=
y.
>
> The reason for doing this is that now with simpledrm, there's no need fo=
r
> the legacy fbdev (e.g: efifb or vesafb) drivers anymore and many distros
> now disable them. > But it would simplify the config a lot fo have a sin=
gle
> Kconfig symbol to disable all fbdev drivers.

I suggest to rephrase this, e.g.:
The reason for doing this is that with simpledrm, mainstream Linux distrib=
utions
like Fedora, SUSE or Ubuntu can then more easily enable the DRM drivers on=
ly
by switching off legacy fbdev drivers with one Kconfig option (e.g. for ef=
ifb or
vesafb).

(note: there are quite many other distributions, e.g. debian and the deriv=
ates,
which still need the fbdev drivers for the various other architectures)

> I've built tested with possible combinations of CONFIG_FB, CONFIG_FB_COR=
E,
> CONFIG_DRM_FBDEV_EMULATION and CONFIG_FB_DEVICE symbols set to 'y' or 'n=
'.
>
> Patch #1 moves the auxdisplay drivers to "Graphics support" Kconfig menu=
,
> patch #2 moves the core fbdev Kconfig symbols to a separate Kconfig file=
,
> patch #3 does the FB symbol split and introduces the FB_CORE symbol and
> finally patch #4 makes the DRM symbol to select FB_CORE if the DRM fbdev
> emualtion support was enabled.
>
> Since this series touches three subsystems (auxdisplay, fbdev and DRM),
> I would like to merge it through DRM with the acks of these maintainers.

Sure. Ack from me.

The patch series look good otherwise. You may add:
Acked-by: Helge Deller <deller@gmx.de>

> This is a v6 of the patch-set that addresses issues pointed out by Arnd
> Bergmann in the previous v5:
>
> https://lists.freedesktop.org/archives/dri-devel/2023-July/413943.html
>
> Changes in v6:
> - Don't move FB_{HECUBA,SVGALIB,MACMODES} to config/Kcore (Arnd Bergmann=
).
> - Fix link error when CONFIG_FB_CORE=3Dy and CONFIG_FB=3Dm (Arnd Bergman=
n).
>
> Changes in v5:
> - Take the auxdisplay/Kconfig source out of "if HAS_IOMEM" (Geert Uytter=
hoeven).
> - Fix ifdef guard check in drivers/video/backlight/backlight.c (Arnd Ber=
gmann).
>
> Changes in v4:
> - Fix menuconfig hierarchy that was broken in v3 (Arnd Bergmann).
>
> Changes in v3:
> - Really make a hidden symbol by removing the prompt (Arnd Bergmann).
> - Change FB_CORE to config instead of menuconfig (Arnd Bergmann).
> - Keep "depends on FB" for FIRMWARE_EDID (Arnd Bergmann).
> - Compile out fb_backlight.o and fbmon.o that are only needed for FB
>    (Arnd Bergmann).
> - Make FB_DEVICE to depend on FB_CORE instead of selecting it.
> - Make the DRM symbol to select FB_CORE if DRM_FBDEV_EMULATION is
>    enabled (Arnd Bergmann).
> - Also make DRM select FB_SYS_HELPERS_DEFERRED if DRM_FBDEV_EMULATION
> - Make DRM_FBDEV_EMULATION to depend on DRM instead of DRM_KMS_HELPER.
>
> Changes in v2:
> - Keep "depends on FB" for FB_DDC, FB_HECUBA, FB_SVGALIB, FB_MACMODES,
>    FB_BACKLIGHT, FB_MODE_HELPERS and FB_TILEBLITTING (Arnd Bergmann).
> - Don't change the fb.o object name (Arnd Bergmann).
> - Make FB_CORE a non-visible Kconfig symbol instead (Thomas Zimmermann).
> - Make CONFIG_DRM_FBDEV_EMULATION to select FB_CORE (Thomas Zimmermann).
>
> Javier Martinez Canillas (4):
>    video: Add auxiliary display drivers to Graphics support menu
>    fbdev: Move core fbdev symbols to a separate Kconfig file
>    fbdev: Split frame buffer support in FB and FB_CORE symbols
>    drm: Make FB_CORE to be selected if DRM fbdev emulation is enabled
>
>   arch/x86/Makefile                   |   2 +-
>   arch/x86/video/Makefile             |   2 +-
>   drivers/Kconfig                     |   2 -
>   drivers/gpu/drm/Kconfig             |   7 +-
>   drivers/video/Kconfig               |   2 +
>   drivers/video/backlight/backlight.c |   6 +-
>   drivers/video/console/Kconfig       |   2 +-
>   drivers/video/fbdev/Kconfig         | 197 ++--------------------------
>   drivers/video/fbdev/core/Kconfig    | 190 +++++++++++++++++++++++++++
>   drivers/video/fbdev/core/Makefile   |  10 +-
>   10 files changed, 218 insertions(+), 202 deletions(-)
>   create mode 100644 drivers/video/fbdev/core/Kconfig
>