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From: Sam Ravnborg <sam@ravnborg.org>
To: dri-devel@lists.freedesktop.org,
	Jingoo Han <jingoohan1@gmail.com>,
	Lee Jones <lee.jones@linaro.org>,
	Daniel Thompson <daniel.thompson@linaro.org>
Cc: Andy Gross <agross@kernel.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	David Airlie <airlied@linux.ie>,
	Emil Velikov <emil.l.velikov@gmail.com>,
	Jonathan Corbet <corbet@lwn.net>,
	linux-arm-msm@vger.kernel.org, linux-pwm@vger.kernel.org,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Michael Hennerich <michael.hennerich@analog.com>,
	patches@opensource.cirrus.com,
	Support Opensource <support.opensource@diasemi.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Uwe Kleine-Konig <u.kleine-koenig@pengutronix.de>,
	Peter Ujfalusi <peter.ujfalusi@ti.com>, Tomi Valkeinen <tomi.v>
Subject: [PATCH v5 04/19] backlight: improve backlight_properties documentation
Date: Sun, 19 Jul 2020 10:07:28 +0200
Message-ID: <20200719080743.8560-5-sam@ravnborg.org> (raw)
In-Reply-To: <20200719080743.8560-1-sam@ravnborg.org>

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

v3:
  - Added missing '@' in kernel-doc

v2:
  - Added into for each field (Daniel)
  - Re-written some parts to explain what to do, rather
    than what not to do.
    Partly based on suggestions from the review (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 | 96 ++++++++++++++++++++++++++++++++++-----
 1 file changed, 85 insertions(+), 11 deletions(-)

diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index dfb43ee02ea0..10518b00b059 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -117,28 +117,102 @@ struct backlight_ops {
 	int (*check_fb)(struct backlight_device *bd, struct fb_info *info);
 };
 
-/* This structure defines all the properties of a backlight */
+/**
+ * struct backlight_properties - backlight properties
+ *
+ * This structure defines all the properties of a backlight.
+ */
 struct backlight_properties {
-	/* Current User requested brightness (0 - max_brightness) */
+	/**
+	 * @brightness: The current brightness requested by the user.
+	 *
+	 * The backlight core makes sure the range is (0 to max_brightness)
+	 * when the brightness is set via the sysfs attribute:
+	 * /sys/class/backlight/<backlight>/brightness.
+	 *
+	 * This value can be set in the backlight_properties passed
+	 * to devm_backlight_device_register() to set a default brightness
+	 * value.
+	 */
 	int brightness;
-	/* Maximal value for brightness (read-only) */
+
+	/**
+	 * @max_brightness: The maximum brightness value.
+	 *
+	 * This value must be set in the backlight_properties passed to
+	 * devm_backlight_device_register() and shall not be modified by the
+	 * driver after registration.
+	 */
 	int max_brightness;
-	/* Current FB Power mode (0: full on, 1..3: power saving
-	   modes; 4: full off), see FB_BLANK_XXX */
+
+	/**
+	 * @power: The current power mode.
+	 *
+	 * User space can configure the power mode using the sysfs
+	 * attribute: /sys/class/backlight/<backlight>/bl_power
+	 * When the power property is updated update_status() is called.
+	 *
+	 * The possible values are: (0: full on, 1 to 3: power saving
+	 * modes; 4: full off), see FB_BLANK_XXX.
+	 *
+	 * When the backlight device is enabled @power is set
+	 * to FB_BLANK_UNBLANK. When the backlight device is disabled
+	 * @power is set to FB_BLANK_POWERDOWN.
+	 */
 	int power;
-	/* FB Blanking active? (values as for power) */
-	/* Due to be removed, please use (state & BL_CORE_FBBLANK) */
+
+	/**
+	 * @fb_blank: The power state from the FBIOBLANK ioclt.
+	 *
+	 * When the FBIOBLANK ioctl is called @fb_blank is set to the
+	 * blank parameter and the update_status() operation is called.
+	 *
+	 * When the backlight device is enabled @fb_blank is set
+	 * to FB_BLANK_UNBLANK. When the backlight device is disabled
+	 * @fb_blank is set to FB_BLANK_POWERDOWN.
+	 *
+	 * Backlight drivers should avoid using this property. It has been
+	 * replaced by state & BL_CORE_FBLANK (although most drivers should
+	 * use backlight_is_blank() as the preferred means to get the blank
+	 * state).
+	 *
+	 * fb_blank is deprecated and will be removed.
+	 */
 	int fb_blank;
-	/* Backlight type */
+
+	/**
+	 * @type: The type of backlight supported.
+	 *
+	 * The backlight type allows userspace to make appropriate
+	 * policy desicions based on the backlight type.
+	 *
+	 * This value must be set in the backlight_properties
+	 * passed to devm_backlight_device_register().
+	 */
 	enum backlight_type type;
-	/* Flags used to signal drivers of state changes */
+
+	/**
+	 * @state: The state of the backlight core.
+	 *
+	 * The state is a bitmask. BL_CORE_FBBLANK is set when the display
+	 * is expected to be blank. BL_CORE_SUSPENDED is set when the
+	 * driver is suspended.
+	 *
+	 * backlight drivers are excpected to use backlight_is_blank()
+	 * in their update_status() operation rather than reading the
+	 * state property.
+	 *
+	 * The state is maintained by the core and drivers may not modify it.
+	 */
 	unsigned int state;
-	/* Type of the brightness scale (linear, non-linear, ...) */
-	enum backlight_scale scale;
 
 #define BL_CORE_SUSPENDED	(1 << 0)	/* backlight is suspended */
 #define BL_CORE_FBBLANK		(1 << 1)	/* backlight is under an fb blank event */
 
+	/**
+	 * @scale: The type of the brightness scale.
+	 */
+	enum backlight_scale scale;
 };
 
 struct backlight_device {
-- 
2.25.1

  parent reply index

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-19  8:07 [PATCH v5 0/19] backlight: backlight updates Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 01/19] backlight: refactor fb_notifier_callback() Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 02/19] backlight: add backlight_is_blank() Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 03/19] backlight: improve backlight_ops documentation Sam Ravnborg
2020-07-19  8:07 ` Sam Ravnborg [this message]
2020-07-19  8:07 ` [PATCH v5 05/19] backlight: improve backlight_device documentation Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 06/19] backlight: document inline functions in backlight.h Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 07/19] backlight: document enums " Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 08/19] backlight: remove the unused backlight_bl driver Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 09/19] backlight: drop extern from prototypes Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 10/19] backlight: add overview and update existing doc Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 11/19] backlight: wire up kernel-doc documentation Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 12/19] backlight: introduce backlight_get_brightness() Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 13/19] backlight: as3711_bl: simplify update_status Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 14/19] backlight: cr_bllcd: introduce gpio-backlight semantics Sam Ravnborg
2020-07-20  8:48   ` Daniel Thompson
2020-07-20  9:14     ` Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 15/19] backlight: gpio_backlight: simplify update_status() Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 16/19] backlight: jornada720_bl: introduce backlight_is_blank() Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 17/19] backlight: use backlight_get_brightness() Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 18/19] backlight: drop backlight_put() Sam Ravnborg
2020-07-19  8:07 ` [PATCH v5 19/19] backlight: make of_find_backlight static Sam Ravnborg
2020-07-20  9:36 ` [PATCH v5 0/19] backlight: backlight updates Lee Jones
2020-07-20 11:01   ` Sam Ravnborg

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