linux-kernel - [PATCH v2 0/2] allow simple{fb,drm} drivers to be used on non-x86 EFI platforms

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Date:   Tue,  1 Jun 2021 16:59:10 +0200
From:   Javier Martinez Canillas <javierm@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Hans de Goede <hdegoede@...hat.com>,
        Peter Robinson <pbrobinson@...il.com>,
        dri-devel@...ts.freedesktop.org, Daniel Vetter <daniel@...ll.ch>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Borislav Petkov <bp@...en8.de>,
        Brijesh Singh <brijesh.singh@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Chester Lin <clin@...e.com>, Dinh Nguyen <dinguyen@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Joerg Roedel <jroedel@...e.de>,
        John Stultz <john.stultz@...aro.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Juergen Gross <jgross@...e.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Russell King <linux@...linux.org.uk>,
        Sudeep Holla <sudeep.holla@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-efi@...r.kernel.org,
        linux-riscv@...ts.infradead.org, x86@...nel.org
Subject: [PATCH v2 0/2] allow simple{fb,drm} drivers to be used on non-x86 EFI platforms

The simplefb and simpledrm drivers match against a "simple-framebuffer"
device, but for aarch64 this is only registered when using Device Trees
and there's a node with a "simple-framebuffer" compatible string.

There is no code to register a "simple-framebuffer" platform device when
using EFI instead. In fact, the only platform device that's registered in
this case is an "efi-framebuffer", which means that the efifb driver is
the only driver supported to have an early console with EFI on aarch64.

The x86 architecture platform has a Generic System Framebuffers (sysfb)
support, that register a system frambuffer platform device. It either
registers a "simple-framebuffer" for the simple{fb,drm} drivers or legacy
VGA/EFI FB devices for the vgafb/efifb drivers.

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 do the latter. It 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.

The series touches different subystems and will need coordination between
maintainers. Ard Biesheuvel said that can be merged through the EFI tree.

Best regards,
Javier

Changes in v2:
- Use default y and depends on X86 instead doing a select in arch/x86/Kconfig.
- Also enable the SYSFB Kconfig option when COMPILE_TEST.
- Improve commit message to explain why is useful for other arches to use this.
- Use "depends on" for the supported architectures instead of selecting it.
- Improve commit message to explain the benefits of reusing sysfb for !X86.

Javier Martinez Canillas (2):
  drivers/firmware: move x86 Generic System Framebuffers support
  drivers/firmware: consolidate EFI framebuffer setup for all arches

 arch/arm/include/asm/efi.h                    |  5 +-
 arch/arm64/include/asm/efi.h                  |  5 +-
 arch/riscv/include/asm/efi.h                  |  5 +-
 arch/x86/Kconfig                              | 26 ------
 arch/x86/kernel/Makefile                      |  3 -
 drivers/firmware/Kconfig                      | 32 +++++++
 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 +++----
 13 files changed, 180 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