Nouveau - Aug 2022 - [PATCH v4 02/31] drm/i915: Don't register backlight when another backlight should be used

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.

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
---
 drivers/gpu/drm/i915/display/intel_backlight.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_backlight.c
b/drivers/gpu/drm/i915/display/intel_backlight.c
index 681ebcda97ad..a4dd7924e0c1 100644
--- a/drivers/gpu/drm/i915/display/intel_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_backlight.c
@@ -8,6 +8,8 @@
 #include <linux/pwm.h>
 #include <linux/string_helpers.h>
 
+#include <acpi/video.h>
+
 #include "intel_backlight.h"
 #include "intel_backlight_regs.h"
 #include "intel_connector.h"
@@ -952,6 +954,11 @@ int intel_backlight_device_register(struct intel_connector
*connector)
 
 	WARN_ON(panel->backlight.max == 0);
 
+	if (!acpi_video_backlight_use_native()) {
+		DRM_INFO("Skipping intel_backlight registration\n");
+		return 0;
+	}
+
 	memset(&props, 0, sizeof(props));
 	props.type = BACKLIGHT_RAW;
 
-- 
2.37.2

On Wed, 24 Aug 2022, 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.
>
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> ---
>  drivers/gpu/drm/i915/display/intel_backlight.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_backlight.c
b/drivers/gpu/drm/i915/display/intel_backlight.c
> index 681ebcda97ad..a4dd7924e0c1 100644
> --- a/drivers/gpu/drm/i915/display/intel_backlight.c
> +++ b/drivers/gpu/drm/i915/display/intel_backlight.c
> @@ -8,6 +8,8 @@
>  #include <linux/pwm.h>
>  #include <linux/string_helpers.h>
>  
> +#include <acpi/video.h>
> +
>  #include "intel_backlight.h"
>  #include "intel_backlight_regs.h"
>  #include "intel_connector.h"
> @@ -952,6 +954,11 @@ int intel_backlight_device_register(struct
intel_connector *connector)
>  
>  	WARN_ON(panel->backlight.max == 0);
>  
> +	if (!acpi_video_backlight_use_native()) {
> +		DRM_INFO("Skipping intel_backlight registration\n");
Could use drm_info with drm_device.

Either way,

Reviewed-by: Jani Nikula <jani.nikula at intel.com>

and ack for merging via whichever tree suits you best.

> +		return 0;
> +	}
> +
>  	memset(&props, 0, sizeof(props));
>  	props.type = BACKLIGHT_RAW;
-- 
Jani Nikula, Intel Open Source Graphics Center