[Intel-gfx] [PATCH v4 05/31] drm/nouveau: Don't register backlight when another backlight should be used (v2)

Hans de Goede
2022-08-24T12:18:04Z

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:
- Add nouveau_acpi_video_backlight_use_native() wrapper to avoid unresolved
symbol errors on non X86

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
drivers/gpu/drm/nouveau/nouveau_acpi.c | 5 +++++
drivers/gpu/drm/nouveau/nouveau_acpi.h | 2 ++
drivers/gpu/drm/nouveau/nouveau_backlight.c | 6 ++++++
3 files changed, 13 insertions(+)

diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c b/drivers/gpu/drm/nouveau/nouveau_acpi.c
index 6140db756d06..1592c9cd7750 100644
--- a/drivers/gpu/drm/nouveau/nouveau_acpi.c
+++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c
@@ -386,3 +386,8 @@ nouveau_acpi_edid(struct drm_device *dev, struct drm_connector *connector)

return kmemdup(edid, EDID_LENGTH, GFP_KERNEL);
}
+
+bool nouveau_acpi_video_backlight_use_native(void)
+{
+ return acpi_video_backlight_use_native();
+}
diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.h b/drivers/gpu/drm/nouveau/nouveau_acpi.h
index 330f9b837066..3c666c30dfca 100644
--- a/drivers/gpu/drm/nouveau/nouveau_acpi.h
+++ b/drivers/gpu/drm/nouveau/nouveau_acpi.h
@@ -11,6 +11,7 @@ void nouveau_register_dsm_handler(void);
void nouveau_unregister_dsm_handler(void);
void nouveau_switcheroo_optimus_dsm(void);
void *nouveau_acpi_edid(struct drm_device *, struct drm_connector *);
+bool nouveau_acpi_video_backlight_use_native(void);
#else
static inline bool nouveau_is_optimus(void) { return false; };
static inline bool nouveau_is_v1_dsm(void) { return false; };
@@ -18,6 +19,7 @@ static inline void nouveau_register_dsm_handler(void) {}
static inline void nouveau_unregister_dsm_handler(void) {}
static inline void nouveau_switcheroo_optimus_dsm(void) {}
static inline void *nouveau_acpi_edid(struct drm_device *dev, struct drm_connector *connector) { return NULL; }
+static inline bool nouveau_acpi_video_backlight_use_native(void) { return true; }
#endif

#endif
diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index a2141d3d9b1d..d2b8f8c13db4 100644
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -38,6 +38,7 @@
#include "nouveau_reg.h"
#include "nouveau_encoder.h"
#include "nouveau_connector.h"
+#include "nouveau_acpi.h"

static struct ida bl_ida;
#define BL_NAME_SIZE 15 // 12 for name + 2 for digits + 1 for '\0'
@@ -405,6 +406,11 @@ nouveau_backlight_init(struct drm_connector *connector)
goto fail_alloc;
}

+ if (!nouveau_acpi_video_backlight_use_native()) {
+ NV_INFO(drm, "Skipping nv_backlight registration\n");
+ goto fail_alloc;
+ }
+
if (!nouveau_get_backlight_name(backlight_name, bl)) {
NV_ERROR(drm, "Failed to retrieve a unique name for the backlight interface\n");
goto fail_alloc;
--
2.37.2