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From: "Rafael J. Wysocki" <rafael@kernel.org>
Date: Thu, 16 May 2024 15:04:27 +0200
Message-ID: <CAJZ5v0gw620SLfxM66FfVeWMTN=dSZZtpH-=mFT_0HsumT3SsA@mail.gmail.com>
Subject: Re: [PATCH] ACPI: video: Fix name collision with architecture's video.o
To: Thomas Zimmermann <tzimmermann@suse.de>
Cc: rafael@kernel.org, lenb@kernel.org, arnd@arndb.de, 
	chaitanya.kumar.borah@intel.com, suresh.kumar.kurmi@intel.com, 
	jani.saarinen@intel.com, linux-acpi@vger.kernel.org, 
	linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, 
	linux-arch@vger.kernel.org, linux-fbdev@vger.kernel.org, 
	dri-devel@lists.freedesktop.org, Hans de Goede <hdegoede@redhat.com>
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CC Hans who has been doing the majority of the ACPI video work.

On Thu, May 16, 2024 at 2:43=E2=80=AFPM Thomas Zimmermann <tzimmermann@suse=
de> wrote:
>
> Commit 2fd001cd3600 ("arch: Rename fbdev header and source files")
> renames the video source files under arch/ such that they does not
> refer to fbdev any longer. The new files named video.o conflict with
> ACPI's video.ko module.

And surely nobody knew or was unable to check upfront that there was a
video.ko already in the kernel.

> Modprobing the ACPI module can then fail with warnings about missing symb=
ols, as shown below.
>
>   (i915_selftest:1107) igt_kmod-WARNING: i915: Unknown symbol acpi_video_=
unregister (err -2)
>   (i915_selftest:1107) igt_kmod-WARNING: i915: Unknown symbol acpi_video_=
register_backlight (err -2)
>   (i915_selftest:1107) igt_kmod-WARNING: i915: Unknown symbol __acpi_vide=
o_get_backlight_type (err -2)
>   (i915_selftest:1107) igt_kmod-WARNING: i915: Unknown symbol acpi_video_=
register (err -2)
>
> Fix this problem by renaming ACPI's video.ko to acpi_video.ko. Also
> rename a related source file and clean up the Makefile.

If you insist on renaming, rename it to backlight.c (and
backlight_detect.c for consistency), because that's what it really is
about.

> Reported-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
> Closes: https://lore.kernel.org/intel-gfx/9dcac6e9-a3bf-4ace-bbdc-f697f76=
7f9e0@suse.de/T/#t
> Tested-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Fixes: 2fd001cd3600 ("arch: Rename fbdev header and source files")
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: linux-arch@vger.kernel.org
> Cc: linux-fbdev@vger.kernel.org
> Cc: dri-devel@lists.freedesktop.org
> ---
>  drivers/acpi/Makefile                            | 5 +++--
>  drivers/acpi/{acpi_video.c =3D> acpi_video_core.c} | 2 +-
>  2 files changed, 4 insertions(+), 3 deletions(-)
>  rename drivers/acpi/{acpi_video.c =3D> acpi_video_core.c} (99%)
>
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 8cc8c0d9c8732..fc9e11f7afbf7 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -84,7 +84,9 @@ obj-$(CONFIG_ACPI_FAN)                +=3D fan.o
>  fan-objs                       :=3D fan_core.o
>  fan-objs                       +=3D fan_attr.o
>
> -obj-$(CONFIG_ACPI_VIDEO)       +=3D video.o
> +obj-$(CONFIG_ACPI_VIDEO)       +=3D acpi_video.o
> +acpi_video-objs                        +=3D acpi_video_core.o video_dete=
ct.o
> +
>  obj-$(CONFIG_ACPI_TAD)         +=3D acpi_tad.o
>  obj-$(CONFIG_ACPI_PCI_SLOT)    +=3D pci_slot.o
>  obj-$(CONFIG_ACPI_PROCESSOR)   +=3D processor.o
> @@ -124,7 +126,6 @@ obj-$(CONFIG_ACPI_CONFIGFS) +=3D acpi_configfs.o
>
>  obj-y                          +=3D pmic/
>
> -video-objs                     +=3D acpi_video.o video_detect.o
>  obj-y                          +=3D dptf/
>
>  obj-$(CONFIG_ARM64)            +=3D arm64/
> diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video_core.c
> similarity index 99%
> rename from drivers/acpi/acpi_video.c
> rename to drivers/acpi/acpi_video_core.c
> index 1fda303882973..32bf81c5773a4 100644
> --- a/drivers/acpi/acpi_video.c
> +++ b/drivers/acpi/acpi_video_core.c
> @@ -1,6 +1,6 @@
>  // SPDX-License-Identifier: GPL-2.0-or-later
>  /*
> - *  video.c - ACPI Video Driver
> + *  acpi_video_core.c - ACPI Video Driver
>   *
>   *  Copyright (C) 2004 Luming Yu <luming.yu@intel.com>
>   *  Copyright (C) 2004 Bruno Ducrot <ducrot@poupinou.org>
> --
> 2.45.0
>
>