[PATCH v5 03/19] backlight: improve backlight_ops documentation

Sam Ravnborg
2020-07-19T08:08:10Z

Improve the documentation for backlight_ops and
adapt it to kernel-doc style.

v2:
- Add intro for each field (Daniel)

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jingoo Han <jingoohan1@gmail.com>
---
include/linux/backlight.h | 59 +++++++++++++++++++++++++++++++++++----
1 file changed, 53 insertions(+), 6 deletions(-)

diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index 56e51ebab740..dfb43ee02ea0 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -55,19 +55,66 @@ enum backlight_scale {
struct backlight_device;
struct fb_info;

+/**
+ * struct backlight_ops - backlight operations
+ *
+ * The backlight operations are specifed when the backlight device is registered.
+ */
struct backlight_ops {
+ /**
+ * @options: Configure how operations are called from the core.
+ *
+ * The options parameter is used to adjust the behaviour of the core.
+ * Set BL_CORE_SUSPENDRESUME to get the update_status() operation called
+ * upon suspend and resume.
+ */
unsigned int options;

#define BL_CORE_SUSPENDRESUME (1 << 0)

- /* Notify the backlight driver some property has changed */
+ /**
+ * @update_status: Operation called when properties have changed.
+ *
+ * Notify the backlight driver some property has changed.
+ * The update_status operation is protected by the update_lock.
+ *
+ * The backlight driver is expected to use backlight_is_blank()
+ * to check if the display is blanked and set brightness accordingly.
+ * update_status() is called when any of the properties has changed.
+ *
+ * RETURNS:
+ *
+ * 0 on sucees, negative error code if any failure occured.
+ */
int (*update_status)(struct backlight_device *);
- /* Return the current backlight brightness (accounting for power,
- fb_blank etc.) */
+
+ /**
+ * @get_brightness: Return the current backlight brightness.
+ *
+ * The driver may implement this as a readback from the HW.
+ * This operation is optional and if not present then the current
+ * brightness property value is used.
+ *
+ * RETURNS:
+ *
+ * A brightness value which is 0 or a positive numer.
+ * On failure a negative error code is returned.
+ */
int (*get_brightness)(struct backlight_device *);
- /* Check if given framebuffer device is the one bound to this backlight;
- return 0 if not, !=0 if it is. If NULL, backlight always matches the fb. */
- int (*check_fb)(struct backlight_device *, struct fb_info *);
+
+ /**
+ * @check_fb: Check the framebuffer device.
+ *
+ * Check if given framebuffer device is the one bound to this backlight.
+ * This operation is optional and if not implemented it is assumed that the
+ * fbdev is always the one bound to the backlight.
+ *
+ * RETURNS:
+ *
+ * If info is NULL or the info matches the fbdev bound to the backlight return true.
+ * If info does not match the fbdev bound to the backlight return false.
+ */
+ int (*check_fb)(struct backlight_device *bd, struct fb_info *info);
};

/* This structure defines all the properties of a backlight */
--
2.25.1