linux-kernel - Re: [PATCH 2/2] drm/efidrm: Match framebuffer device by id instead of driver name

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Message-ID: <2daa5756-fac5-41b1-a21a-54290112df7a@suse.de>
Date: Mon, 18 Aug 2025 09:19:49 +0200
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Yao Zi <ziyao@...root.org>, Javier Martinez Canillas
 <javierm@...hat.com>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] drm/efidrm: Match framebuffer device by id instead of
 driver name

Hi

Am 16.08.25 um 17:34 schrieb Yao Zi:
> Currently the driver matches the platform framebuffer device registered
> by sysfb through driver name, "efi-framebuffer", this is a little
> confusing since this driver registers a DRM device, instead of a
> framebuffer.
>
> Moreover, we have a driver with the same name, enabled by CONFIG_FB_EFI,
> that acts as a consumer of efi-framebuffer as well. They cannot be both
> loaded into the kernel.
>
> Making these two drivers coexist is sometimes useful, e.g., a
> distribution may want to build fbcon into the kernel image for debugging
> purpose, but keep the whole DRM subsystem enabled as module. In such
> case efidrm could serve as a solution for running DRM-specific userspace
> programs on platforms with only UEFI framebuffer supplied.
>
> Let's rename the driver as "efi-display" to avoid possible confusion.
> A platform_device_id table is introduced to match "efi-framebuffer"
> devices.

NAK, please see the rsp vesa-framebuffer patch for the rational

https://lore.kernel.org/dri-devel/d74f16f0-9615-4816-a49c-efa35b9ab344@suse.de/

Best regards
Thomas

>
> Signed-off-by: Yao Zi <ziyao@...root.org>
> ---
>   drivers/gpu/drm/sysfb/efidrm.c | 10 +++++++++-
>   1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/sysfb/efidrm.c b/drivers/gpu/drm/sysfb/efidrm.c
> index 1883c4a8604c..7f76e8961788 100644
> --- a/drivers/gpu/drm/sysfb/efidrm.c
> +++ b/drivers/gpu/drm/sysfb/efidrm.c
> @@ -3,6 +3,7 @@
>   #include <linux/aperture.h>
>   #include <linux/efi.h>
>   #include <linux/limits.h>
> +#include <linux/mod_devicetable.h>
>   #include <linux/platform_device.h>
>   #include <linux/screen_info.h>
>   
> @@ -375,10 +376,17 @@ static void efidrm_remove(struct platform_device *pdev)
>   	drm_dev_unplug(dev);
>   }
>   
> +static const struct platform_device_id efidrm_platform_id[] = {
> +	{ "efi-framebuffer" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(platform, efidrm_platform_id);
> +
>   static struct platform_driver efidrm_platform_driver = {
>   	.driver = {
> -		.name = "efi-framebuffer",
> +		.name = "efi-display",
>   	},
> +	.id_table = efidrm_platform_id,
>   	.probe = efidrm_probe,
>   	.remove = efidrm_remove,
>   };

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)