Re: [PATCH 0/2] allow the sysfb support to be used in non-x86 arches

From: Ard Biesheuvel <ardb@kernel.org>
To: Javier Martinez Canillas <javierm@redhat.com>
Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	 Daniel Vetter <daniel@ffwll.ch>,
	Peter Robinson <pbrobinson@gmail.com>,
	 Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@linux.ie>,
	 Hans de Goede <hdegoede@redhat.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	 Borislav Petkov <bp@alien8.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	"H. Peter Anvin" <hpa@zytor.com>,  Ingo Molnar <mingo@redhat.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	 Paul Walmsley <paul.walmsley@sifive.com>,
	Russell King <linux@armlinux.org.uk>,
	Thomas Gleixner <tglx@linutronix.de>,
	Will Deacon <will@kernel.org>,
	 linux-arm-kernel@lists.infradead.org, linux-efi@vger.kernel.org,
	 linux-riscv@lists.infradead.org, x86@kernel.org
Subject: Re: [PATCH 0/2] allow the sysfb support to be used in non-x86 arches
Date: Mon, 24 May 2021 12:24:32 +0200	[thread overview]
Message-ID: <CAMj1kXGrDm5yN5eRZJ0YAjCde=0Xw7hobC9Oz5CNovo0sWuM+g@mail.gmail.com> (raw)
In-Reply-To: <20210521192907.3040644-1-javierm@redhat.com>

Hello Javier,

On Fri, 21 May 2021 at 21:29, Javier Martinez Canillas
<javierm@redhat.com> wrote:
>
> The x86 architecture platform has a Generic System Framebuffers (sysfb)
> support, that register a system frambuffer platform devices. It either
> registers a "simple-framebuffer" for the simple{fb,drm} drivers or legacy
> VGA/EFI FB devices for the vgafb/efifb drivers.
>
> Besides this, the EFI initialization code used by other architectures such
> as aarch64 and riscv, has similar logic but only register an EFI FB device.
>
> The sysfb is generic enough to be reused by other architectures and can be
> moved out of the arch/x86 directory to drivers/firmware, allowing the EFI
> logic used by non-x86 architectures to be folded into sysfb as well.
>
> Patch #1 in this series do the former while patch #2 the latter. This has
> been tested on x86_64 and aarch64 machines using the efifb, simplefb and
> simpledrm drivers. But more testing will be highly appreciated, to make
> sure that no regressions are being introduced by these changes.
>
> Since this touches both arch/{x86,arm,arm64,riscv} and drivers/firmware, I
> don't know how it should be merged. But I didn't find a way to split these.
>

We could merge this via the EFI tree without too much risk of
conflicts, I think.

However, I'd like to see a better explanation of why this is an improvement.
The diffstat does not show a huge net win, and it does not enable
anything we didn't already have before, right?

>
> Javier Martinez Canillas (2):
>   drivers/firmware: move x86 Generic System Framebuffers support
>   drivers/firmware: consolidate EFI framebuffer setup for all arches
>
>  arch/arm/Kconfig                              |  1 +
>  arch/arm/include/asm/efi.h                    |  5 +-
>  arch/arm64/Kconfig                            |  1 +
>  arch/arm64/include/asm/efi.h                  |  5 +-
>  arch/riscv/Kconfig                            |  1 +
>  arch/riscv/include/asm/efi.h                  |  5 +-
>  arch/x86/Kconfig                              | 27 +-----
>  arch/x86/kernel/Makefile                      |  3 -
>  drivers/firmware/Kconfig                      | 30 +++++++
>  drivers/firmware/Makefile                     |  2 +
>  drivers/firmware/efi/Makefile                 |  2 +
>  drivers/firmware/efi/efi-init.c               | 90 -------------------
>  .../firmware/efi}/sysfb_efi.c                 | 79 +++++++++++++++-
>  {arch/x86/kernel => drivers/firmware}/sysfb.c | 42 +++++----
>  .../firmware}/sysfb_simplefb.c                | 31 ++++---
>  .../x86/include/asm => include/linux}/sysfb.h | 34 +++----
>  16 files changed, 182 insertions(+), 176 deletions(-)
>  rename {arch/x86/kernel => drivers/firmware/efi}/sysfb_efi.c (84%)
>  rename {arch/x86/kernel => drivers/firmware}/sysfb.c (70%)
>  rename {arch/x86/kernel => drivers/firmware}/sysfb_simplefb.c (82%)
>  rename {arch/x86/include/asm => include/linux}/sysfb.h (68%)
>
> --
> 2.31.1
>

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