[PATCH v2 04/29] drm/radeon: Don't register backlight when another backlight should be used

[Alex Deucher]

On Tue, Jul 12, 2022 at 3:39 PM Hans de Goede <hdegoede at redhat.com> wrote:
>
> Before this commit when we want userspace to use the acpi_video backlight
> device we register both the GPU's native backlight device and acpi_video's
> firmware acpi_video# backlight device. This relies on userspace preferring
> firmware type backlight devices over native ones.
>
> Registering 2 backlight devices for a single display really is
> undesirable, don't register the GPU's native backlight device when
> another backlight device should be used.
>
> Changes in v2:
> - To avoid linker errors when radeon is builtin and video_detect.c is in
>   a module, select ACPI_VIDEO and its deps if ACPI && X86 are enabled.
>   When these are not set, ACPI_VIDEO is disabled, ensuring the stubs
>   from acpi/video.h will be used.
>
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>

Acked-by: Alex Deucher <alexander.deucher at amd.com>

> ---
>  drivers/gpu/drm/Kconfig                         | 6 ++++++
>  drivers/gpu/drm/radeon/atombios_encoders.c      | 7 +++++++
>  drivers/gpu/drm/radeon/radeon_legacy_encoders.c | 7 +++++++
>  3 files changed, 20 insertions(+)
>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index d65119860760..a07b76e06f84 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -234,6 +234,12 @@ config DRM_RADEON
>         select HWMON
>         select BACKLIGHT_CLASS_DEVICE
>         select INTERVAL_TREE
> +       # radeon depends on ACPI_VIDEO when X86 and ACPI are both enabled
> +       # for select to work, ACPI_VIDEO's dependencies must also be selected
> +       select INPUT if ACPI && X86
> +       select X86_PLATFORM_DEVICES if ACPI && X86
> +       select ACPI_WMI if ACPI && X86
> +       select ACPI_VIDEO if ACPI && X86
>         help
>           Choose this option if you have an ATI Radeon graphics card.  There
>           are both PCI and AGP versions.  You don't need to choose this to
> diff --git a/drivers/gpu/drm/radeon/atombios_encoders.c b/drivers/gpu/drm/radeon/atombios_encoders.c
> index c93040e60d04..958920230d6f 100644
> --- a/drivers/gpu/drm/radeon/atombios_encoders.c
> +++ b/drivers/gpu/drm/radeon/atombios_encoders.c
> @@ -32,6 +32,8 @@
>  #include <drm/drm_file.h>
>  #include <drm/radeon_drm.h>
>
> +#include <acpi/video.h>
> +
>  #include "atom.h"
>  #include "radeon_atombios.h"
>  #include "radeon.h"
> @@ -209,6 +211,11 @@ void radeon_atom_backlight_init(struct radeon_encoder *radeon_encoder,
>         if (!(rdev->mode_info.firmware_flags & ATOM_BIOS_INFO_BL_CONTROLLED_BY_GPU))
>                 return;
>
> +       if (!acpi_video_backlight_use_native()) {
> +               DRM_INFO("Skipping radeon atom DIG backlight registration\n");
> +               return;
> +       }
> +
>         pdata = kmalloc(sizeof(struct radeon_backlight_privdata), GFP_KERNEL);
>         if (!pdata) {
>                 DRM_ERROR("Memory allocation failed\n");
> diff --git a/drivers/gpu/drm/radeon/radeon_legacy_encoders.c b/drivers/gpu/drm/radeon/radeon_legacy_encoders.c
> index 1a66fb969ee7..d24cedf20c47 100644
> --- a/drivers/gpu/drm/radeon/radeon_legacy_encoders.c
> +++ b/drivers/gpu/drm/radeon/radeon_legacy_encoders.c
> @@ -33,6 +33,8 @@
>  #include <drm/drm_util.h>
>  #include <drm/radeon_drm.h>
>
> +#include <acpi/video.h>
> +
>  #include "radeon.h"
>  #include "radeon_asic.h"
>  #include "radeon_legacy_encoders.h"
> @@ -387,6 +389,11 @@ void radeon_legacy_backlight_init(struct radeon_encoder *radeon_encoder,
>                 return;
>  #endif
>
> +       if (!acpi_video_backlight_use_native()) {
> +               DRM_INFO("Skipping radeon legacy LVDS backlight registration\n");
> +               return;
> +       }
> +
>         pdata = kmalloc(sizeof(struct radeon_backlight_privdata), GFP_KERNEL);
>         if (!pdata) {
>                 DRM_ERROR("Memory allocation failed\n");
> --
> 2.36.0
>