[PATCH v2 03/29] drm/amdgpu: Don't register backlight when another backlight should be used

[Alex Deucher]

On Wed, Jul 20, 2022 at 12:44 PM Alex Deucher <alexdeucher at gmail.com> wrote:
>
> 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 amdgpu 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>

Actually, can you use dev_info for the messages below rather than
DRM_INFO?  That makes it easier to tell which GPU is affected in a
multi-GPU system.  With that changed,
Acked-by: Alex Deucher <alexander.deucher at amd.com>

>
> > ---
> >  drivers/gpu/drm/Kconfig                           | 6 ++++++
> >  drivers/gpu/drm/amd/amdgpu/atombios_encoders.c    | 7 +++++++
> >  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 7 +++++++
> >  3 files changed, 20 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> > index aaa7ad1f0614..d65119860760 100644
> > --- a/drivers/gpu/drm/Kconfig
> > +++ b/drivers/gpu/drm/Kconfig
> > @@ -258,6 +258,12 @@ config DRM_AMDGPU
> >         select HWMON
> >         select BACKLIGHT_CLASS_DEVICE
> >         select INTERVAL_TREE
> > +       # amdgpu 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 a recent AMD Radeon graphics card.
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c b/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
> > index fa7421afb9a6..abf209e36fca 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/atombios_encoders.c
> > @@ -26,6 +26,8 @@
> >
> >  #include <linux/pci.h>
> >
> > +#include <acpi/video.h>
> > +
> >  #include <drm/drm_crtc_helper.h>
> >  #include <drm/amdgpu_drm.h>
> >  #include "amdgpu.h"
> > @@ -184,6 +186,11 @@ void amdgpu_atombios_encoder_init_backlight(struct amdgpu_encoder *amdgpu_encode
> >         if (!(adev->mode_info.firmware_flags & ATOM_BIOS_INFO_BL_CONTROLLED_BY_GPU))
> >                 return;
> >
> > +       if (!acpi_video_backlight_use_native()) {
> > +               DRM_INFO("Skipping amdgpu atom DIG backlight registration\n");
> > +               return;
> > +       }
> > +
> >         pdata = kmalloc(sizeof(struct amdgpu_backlight_privdata), GFP_KERNEL);
> >         if (!pdata) {
> >                 DRM_ERROR("Memory allocation failed\n");
> > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > index 5eb111d35793..3b03a95e59a8 100644
> > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> > @@ -86,6 +86,8 @@
> >  #include <drm/drm_audio_component.h>
> >  #include <drm/drm_gem_atomic_helper.h>
> >
> > +#include <acpi/video.h>
> > +
> >  #include "ivsrcid/dcn/irqsrcs_dcn_1_0.h"
> >
> >  #include "dcn/dcn_1_0_offset.h"
> > @@ -4050,6 +4052,11 @@ amdgpu_dm_register_backlight_device(struct amdgpu_display_manager *dm)
> >         amdgpu_dm_update_backlight_caps(dm, dm->num_of_edps);
> >         dm->brightness[dm->num_of_edps] = AMDGPU_MAX_BL_LEVEL;
> >
> > +       if (!acpi_video_backlight_use_native()) {
> > +               DRM_INFO("Skipping amdgpu DM backlight registration\n");
> > +               return;
> > +       }
> > +
> >         props.max_brightness = AMDGPU_MAX_BL_LEVEL;
> >         props.brightness = AMDGPU_MAX_BL_LEVEL;
> >         props.type = BACKLIGHT_RAW;
> > --
> > 2.36.0
> >