linux-kernel - Re: [PATCH 0/3] video/efi: Support FIRMWARE

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Message-ID: <4ca283ad-c549-4da4-93f9-e3cf17ab45a4@suse.de>
Date: Thu, 20 Nov 2025 08:56:10 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Ard Biesheuvel <ardb+git@...gle.com>, linux-efi@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>,
 Javier Martinez Canillas <javierm@...hat.com>
Subject: Re: [PATCH 0/3] video/efi: Support FIRMWARE_EDID on non-x86

Hi,

thanks for addressing the remaining EDID support.

First of all, you need to cc dri-devel@...ts.freedesktop.org  on any 
further revisions.

Am 19.11.25 um 13:30 schrieb Ard Biesheuvel:
> From: Ard Biesheuvel <ardb@...nel.org>
>
> Refactor the screen_info handling so non-x86 platforms booting via the
> EFI stub also have access to the EDID data exposed by the EFI boot
> services.

I don't like how this series complicates everything to make non-x86 
easier. But the general idea of using efi_screen_info goes into the 
right direction. It's just not generic enough.

The sysfb code transfers struct screen_info as device parameter [1]. 
Drivers later fetch it on probe [2].  The direct ref to the global 
edid_info [3] only exists because we have no means of transferring it as 
device data.

So instead of using efi_screen_info, let's declare struct sysfb_display 
with screen_info and edid_info.  The header would be linux/sysfb.h.  We 
transfer this to all related drivers.  The generic EFI code would set it 
up like efi_screen_info and the x86 code would decalre it at [4]; 
replacing the existing state.

Best regards
Thomas

[1] 
https://elixir.bootlin.com/linux/v6.17.8/source/drivers/firmware/sysfb.c#L205
[2] 
https://elixir.bootlin.com/linux/v6.17.8/source/drivers/gpu/drm/sysfb/efidrm.c#L162
[3] 
https://elixir.bootlin.com/linux/v6.17.8/source/drivers/gpu/drm/sysfb/efidrm.c#L206
[4] 
https://elixir.bootlin.com/linux/v6.17.8/source/arch/x86/kernel/setup.c#L214


>
> Cc: Thomas Zimmermann <tzimmermann@...e.de>
> Cc: Javier Martinez Canillas <javierm@...hat.com>
>
> Ard Biesheuvel (3):
>    efi: Wrap screen_info in efi_screen_info so edid_info can be added
>      later
>    video/edid: Use getter function for edid_info
>    efi: Add FIRMWARE_EDID support
>
>   arch/x86/kernel/setup.c                       |  8 ++++++--
>   drivers/firmware/efi/earlycon.c               |  1 -
>   drivers/firmware/efi/efi-init.c               | 19 ++++++++++++++-----
>   drivers/firmware/efi/libstub/efi-stub-entry.c |  3 +--
>   drivers/firmware/efi/libstub/efi-stub.c       | 16 ++++++++++------
>   drivers/firmware/efi/libstub/efistub.h        |  9 +++------
>   drivers/firmware/efi/libstub/gop.c            |  1 -
>   drivers/firmware/efi/libstub/screen_info.c    |  7 +++----
>   drivers/firmware/efi/libstub/zboot.c          |  2 +-
>   drivers/firmware/efi/sysfb_efi.c              |  1 -
>   drivers/gpu/drm/sysfb/efidrm.c                |  4 ++--
>   drivers/gpu/drm/sysfb/vesadrm.c               |  4 ++--
>   drivers/video/Kconfig                         |  2 +-
>   drivers/video/fbdev/core/fbmon.c              |  4 ++--
>   include/linux/efi.h                           | 10 +++++++++-
>   include/video/edid.h                          |  2 +-
>   16 files changed, 55 insertions(+), 38 deletions(-)
>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)