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ACPI: video: Add comment about acpi_video_backlight_use_native() usage

Message ID 20231026135303.48757-1-hdegoede@redhat.com (mailing list archive)
State Mainlined, archived
Headers show
Series ACPI: video: Add comment about acpi_video_backlight_use_native() usage | expand

Commit Message

Hans de Goede Oct. 26, 2023, 1:53 p.m. UTC
Add a comment explaining that acpi_video_backlight_use_native() MUST
only be used by GPU drivers and that it must NOT be used on other places.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
The main reason for writing this patch is that some recent submitted
patches actually were using acpi_video_backlight_use_native() wrong.
---
 include/acpi/video.h | 9 +++++++++
 1 file changed, 9 insertions(+)

Comments

Rafael J. Wysocki Nov. 20, 2023, 4:48 p.m. UTC | #1
On Thu, Oct 26, 2023 at 3:53 PM Hans de Goede <hdegoede@redhat.com> wrote:
>
> Add a comment explaining that acpi_video_backlight_use_native() MUST
> only be used by GPU drivers and that it must NOT be used on other places.
>
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
> The main reason for writing this patch is that some recent submitted
> patches actually were using acpi_video_backlight_use_native() wrong.
> ---
>  include/acpi/video.h | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/include/acpi/video.h b/include/acpi/video.h
> index 4230392b5b0b..3d538d4178ab 100644
> --- a/include/acpi/video.h
> +++ b/include/acpi/video.h
> @@ -75,6 +75,15 @@ static inline enum acpi_backlight_type acpi_video_get_backlight_type(void)
>         return __acpi_video_get_backlight_type(false, NULL);
>  }
>
> +/*
> + * This function MUST only be called by GPU drivers to check if the driver
> + * should register a backlight class device. This function not only checks
> + * if a GPU native backlight device should be registered it *also* tells
> + * the ACPI video-detect code that native GPU backlight control is available.
> + * Therefor calling this from any place other then the GPU driver is wrong!
> + * To check if GPU native backlight control is used in other places instead use:
> + *   if (acpi_video_get_backlight_type() == acpi_backlight_native) { ... }
> + */
>  static inline bool acpi_video_backlight_use_native(void)
>  {
>         return __acpi_video_get_backlight_type(true, NULL) == acpi_backlight_native;
> --

Applied as 6.8 material, thanks!
diff mbox series

Patch

diff --git a/include/acpi/video.h b/include/acpi/video.h
index 4230392b5b0b..3d538d4178ab 100644
--- a/include/acpi/video.h
+++ b/include/acpi/video.h
@@ -75,6 +75,15 @@  static inline enum acpi_backlight_type acpi_video_get_backlight_type(void)
 	return __acpi_video_get_backlight_type(false, NULL);
 }
 
+/*
+ * This function MUST only be called by GPU drivers to check if the driver
+ * should register a backlight class device. This function not only checks
+ * if a GPU native backlight device should be registered it *also* tells
+ * the ACPI video-detect code that native GPU backlight control is available.
+ * Therefor calling this from any place other then the GPU driver is wrong!
+ * To check if GPU native backlight control is used in other places instead use:
+ *   if (acpi_video_get_backlight_type() == acpi_backlight_native) { ... }
+ */
 static inline bool acpi_video_backlight_use_native(void)
 {
 	return __acpi_video_get_backlight_type(true, NULL) == acpi_backlight_native;