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

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Message-ID: <3bae83d1-bb88-49d3-94a3-3aa56da93bf9@suse.de>
Date: Thu, 20 Nov 2025 09:19:42 +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



Am 20.11.25 um 08:56 schrieb Thomas Zimmermann:
> 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.

If this proposal works for EFI, I could do the changes in graphics 
drivers and then resubmit the EDID series with an additional patch for 
generic EFI.

>
> 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)