diff mbox series

[v2,06/16] backlight: improve backlight_device documentation

Message ID 20200517190139.740249-7-sam@ravnborg.org
State New
Headers show
Series backlight updates | expand

Commit Message

Sam Ravnborg May 17, 2020, 7:01 p.m. UTC
Improve the documentation for backlight_device and
adapt it to kernel-doc style.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jingoo Han <jingoohan1@gmail.com>
---
 include/linux/backlight.h | 81 ++++++++++++++++++++++++++++-----------
 1 file changed, 58 insertions(+), 23 deletions(-)

Comments

Daniel Thompson May 18, 2020, 4:03 p.m. UTC | #1
On Sun, May 17, 2020 at 09:01:29PM +0200, Sam Ravnborg wrote:
> Improve the documentation for backlight_device and
> adapt it to kernel-doc style.
> 
> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Daniel Thompson <daniel.thompson@linaro.org>
> Cc: Jingoo Han <jingoohan1@gmail.com>
> ---
>  include/linux/backlight.h | 81 ++++++++++++++++++++++++++++-----------
>  1 file changed, 58 insertions(+), 23 deletions(-)
> 
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index 7f9cef299d6e..e2d72936bf05 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -14,21 +14,6 @@
>  #include <linux/mutex.h>
>  #include <linux/notifier.h>
>  
> -/* Notes on locking:
> - *
> - * backlight_device->ops_lock is an internal backlight lock protecting the
> - * ops pointer and no code outside the core should need to touch it.
> - *
> - * Access to update_status() is serialised by the update_lock mutex since
> - * most drivers seem to need this and historically get it wrong.
> - *
> - * Most drivers don't need locking on their get_brightness() method.
> - * If yours does, you need to implement it in the driver. You can use the
> - * update_lock mutex if appropriate.
> - *
> - * Any other use of the locks below is probably wrong.
> - */
> -
>  enum backlight_update_reason {
>  	BACKLIGHT_UPDATE_HOTKEY,
>  	BACKLIGHT_UPDATE_SYSFS,
> @@ -221,30 +206,80 @@ struct backlight_properties {
>  	enum backlight_scale scale;
>  };
>  
> +/**
> + * struct backlight_device - backlight device data
> + *
> + * This structure holds all data required by a backlight device.
> + */
>  struct backlight_device {
> -	/* Backlight properties */
> +	/**
> +	 * @props:
> +	 *

As last patch. Why no brief descriptions?


> +	 * Backlight properties
> +	 */
>  	struct backlight_properties props;
>  
> -	/* Serialise access to update_status method */
> +	/**
> +	 * @update_lock:
> +	 *
> +	 * update_lock is an internal backlight lock that serialise access
> +	 * to the update_status() method. The iupdate_lock mutex shall not be used
> +	 * by backlight drivers.

In addition to the typo this directly contradicts the advice in the
original "Notes on locking".

A change this dramatic needs to be fully explaining in the patch
description.


Daniel.


> +	 */
>  	struct mutex update_lock;
>  
> -	/* This protects the 'ops' field. If 'ops' is NULL, the driver that
> -	   registered this device has been unloaded, and if class_get_devdata()
> -	   points to something in the body of that driver, it is also invalid. */
> +	/**
> +	 * @ops_lock:
> +	 *
> +	 * ops_lock is an internal backlight lock that protects the ops pointer
> +	 * and is used around all accesses to ops and when the operations are
> +	 * invoked. The mutex shall not be used by backlight drivers.
> +	 */
>  	struct mutex ops_lock;
> +
> +	/**
> +	 * @ops:
> +	 *
> +	 * Pointer to the backlight operations. If ops is NULL, the driver that
> +	 * registered this device has been unloaded, and if class_get_devdata()
> +	 * points to something in the body of that driver, it is also invalid.
> +	 */
>  	const struct backlight_ops *ops;
>  
> -	/* The framebuffer notifier block */
> +	/**
> +	 * @fb_notif:
> +	 *
> +	 * The framebuffer notifier block
> +	 */
>  	struct notifier_block fb_notif;
>  
> -	/* list entry of all registered backlight devices */
> +	/**
> +	 * @entry:
> +	 *
> +	 * List entry of all registered backlight devices
> +	 */
>  	struct list_head entry;
>  
> +	/**
> +	 * @dev:
> +	 *
> +	 * Parent device.
> +	 */
>  	struct device dev;
>  
> -	/* Multiple framebuffers may share one backlight device */
> +	/**
> +	 * @fb_bl_on:
> +	 *
> +	 * Multiple fbdev's may share one backlight device. The fb_bl_on
> +	 * records the state of the individual fbdev.
> +	 */
>  	bool fb_bl_on[FB_MAX];
>  
> +	/**
> +	 * @use_count:
> +	 *
> +	 * The number of uses of fb_bl_on.
> +	 */
>  	int use_count;
>  };
>  
> -- 
> 2.25.1
>
Jani Nikula May 18, 2020, 5:03 p.m. UTC | #2
On Mon, 18 May 2020, Daniel Thompson <daniel.thompson@linaro.org> wrote:
> On Sun, May 17, 2020 at 09:01:29PM +0200, Sam Ravnborg wrote:
>> Improve the documentation for backlight_device and
>> adapt it to kernel-doc style.
>> 
>> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
>> Cc: Lee Jones <lee.jones@linaro.org>
>> Cc: Daniel Thompson <daniel.thompson@linaro.org>
>> Cc: Jingoo Han <jingoohan1@gmail.com>
>> ---
>>  include/linux/backlight.h | 81 ++++++++++++++++++++++++++++-----------
>>  1 file changed, 58 insertions(+), 23 deletions(-)
>> 
>> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
>> index 7f9cef299d6e..e2d72936bf05 100644
>> --- a/include/linux/backlight.h
>> +++ b/include/linux/backlight.h
>> @@ -14,21 +14,6 @@
>>  #include <linux/mutex.h>
>>  #include <linux/notifier.h>
>>  
>> -/* Notes on locking:
>> - *
>> - * backlight_device->ops_lock is an internal backlight lock protecting the
>> - * ops pointer and no code outside the core should need to touch it.
>> - *
>> - * Access to update_status() is serialised by the update_lock mutex since
>> - * most drivers seem to need this and historically get it wrong.
>> - *
>> - * Most drivers don't need locking on their get_brightness() method.
>> - * If yours does, you need to implement it in the driver. You can use the
>> - * update_lock mutex if appropriate.
>> - *
>> - * Any other use of the locks below is probably wrong.
>> - */
>> -
>>  enum backlight_update_reason {
>>  	BACKLIGHT_UPDATE_HOTKEY,
>>  	BACKLIGHT_UPDATE_SYSFS,
>> @@ -221,30 +206,80 @@ struct backlight_properties {
>>  	enum backlight_scale scale;
>>  };
>>  
>> +/**
>> + * struct backlight_device - backlight device data
>> + *
>> + * This structure holds all data required by a backlight device.
>> + */
>>  struct backlight_device {
>> -	/* Backlight properties */
>> +	/**
>> +	 * @props:
>> +	 *
>
> As last patch. Why no brief descriptions?

There are no "brief descriptions" in kernel-doc struct member inline
markup.

It would be possible to shorten this to:

	/**
	 * @props: Backlight properties
	 */

BR,
Jani.


>
>
>> +	 * Backlight properties
>> +	 */
>>  	struct backlight_properties props;
>>  
>> -	/* Serialise access to update_status method */
>> +	/**
>> +	 * @update_lock:
>> +	 *
>> +	 * update_lock is an internal backlight lock that serialise access
>> +	 * to the update_status() method. The iupdate_lock mutex shall not be used
>> +	 * by backlight drivers.
>
> In addition to the typo this directly contradicts the advice in the
> original "Notes on locking".
>
> A change this dramatic needs to be fully explaining in the patch
> description.
>
>
> Daniel.
>
>
>> +	 */
>>  	struct mutex update_lock;
>>  
>> -	/* This protects the 'ops' field. If 'ops' is NULL, the driver that
>> -	   registered this device has been unloaded, and if class_get_devdata()
>> -	   points to something in the body of that driver, it is also invalid. */
>> +	/**
>> +	 * @ops_lock:
>> +	 *
>> +	 * ops_lock is an internal backlight lock that protects the ops pointer
>> +	 * and is used around all accesses to ops and when the operations are
>> +	 * invoked. The mutex shall not be used by backlight drivers.
>> +	 */
>>  	struct mutex ops_lock;
>> +
>> +	/**
>> +	 * @ops:
>> +	 *
>> +	 * Pointer to the backlight operations. If ops is NULL, the driver that
>> +	 * registered this device has been unloaded, and if class_get_devdata()
>> +	 * points to something in the body of that driver, it is also invalid.
>> +	 */
>>  	const struct backlight_ops *ops;
>>  
>> -	/* The framebuffer notifier block */
>> +	/**
>> +	 * @fb_notif:
>> +	 *
>> +	 * The framebuffer notifier block
>> +	 */
>>  	struct notifier_block fb_notif;
>>  
>> -	/* list entry of all registered backlight devices */
>> +	/**
>> +	 * @entry:
>> +	 *
>> +	 * List entry of all registered backlight devices
>> +	 */
>>  	struct list_head entry;
>>  
>> +	/**
>> +	 * @dev:
>> +	 *
>> +	 * Parent device.
>> +	 */
>>  	struct device dev;
>>  
>> -	/* Multiple framebuffers may share one backlight device */
>> +	/**
>> +	 * @fb_bl_on:
>> +	 *
>> +	 * Multiple fbdev's may share one backlight device. The fb_bl_on
>> +	 * records the state of the individual fbdev.
>> +	 */
>>  	bool fb_bl_on[FB_MAX];
>>  
>> +	/**
>> +	 * @use_count:
>> +	 *
>> +	 * The number of uses of fb_bl_on.
>> +	 */
>>  	int use_count;
>>  };
>>  
>> -- 
>> 2.25.1
>>
Daniel Thompson May 18, 2020, 5:58 p.m. UTC | #3
On Mon, May 18, 2020 at 08:03:21PM +0300, Jani Nikula wrote:
> On Mon, 18 May 2020, Daniel Thompson <daniel.thompson@linaro.org> wrote:
> > On Sun, May 17, 2020 at 09:01:29PM +0200, Sam Ravnborg wrote:
> >> Improve the documentation for backlight_device and
> >> adapt it to kernel-doc style.
> >> 
> >> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
> >> Cc: Lee Jones <lee.jones@linaro.org>
> >> Cc: Daniel Thompson <daniel.thompson@linaro.org>
> >> Cc: Jingoo Han <jingoohan1@gmail.com>
> >> ---
> >>  include/linux/backlight.h | 81 ++++++++++++++++++++++++++++-----------
> >>  1 file changed, 58 insertions(+), 23 deletions(-)
> >> 
> >> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> >> index 7f9cef299d6e..e2d72936bf05 100644
> >> --- a/include/linux/backlight.h
> >> +++ b/include/linux/backlight.h
> >> @@ -14,21 +14,6 @@
> >>  #include <linux/mutex.h>
> >>  #include <linux/notifier.h>
> >>  
> >> -/* Notes on locking:
> >> - *
> >> - * backlight_device->ops_lock is an internal backlight lock protecting the
> >> - * ops pointer and no code outside the core should need to touch it.
> >> - *
> >> - * Access to update_status() is serialised by the update_lock mutex since
> >> - * most drivers seem to need this and historically get it wrong.
> >> - *
> >> - * Most drivers don't need locking on their get_brightness() method.
> >> - * If yours does, you need to implement it in the driver. You can use the
> >> - * update_lock mutex if appropriate.
> >> - *
> >> - * Any other use of the locks below is probably wrong.
> >> - */
> >> -
> >>  enum backlight_update_reason {
> >>  	BACKLIGHT_UPDATE_HOTKEY,
> >>  	BACKLIGHT_UPDATE_SYSFS,
> >> @@ -221,30 +206,80 @@ struct backlight_properties {
> >>  	enum backlight_scale scale;
> >>  };
> >>  
> >> +/**
> >> + * struct backlight_device - backlight device data
> >> + *
> >> + * This structure holds all data required by a backlight device.
> >> + */
> >>  struct backlight_device {
> >> -	/* Backlight properties */
> >> +	/**
> >> +	 * @props:
> >> +	 *
> >
> > As last patch. Why no brief descriptions?
> 
> There are no "brief descriptions" in kernel-doc struct member inline
> markup.
> 
> It would be possible to shorten this to:
> 
> 	/**
> 	 * @props: Backlight properties
> 	 */

Sorry. Loose phrasing on my part... basically the question is why
deviate from the form proposed in "Writing kernel-doc comments"?


Daniel.



> >
> >> +	 * Backlight properties
> >> +	 */
> >>  	struct backlight_properties props;
> >>  
> >> -	/* Serialise access to update_status method */
> >> +	/**
> >> +	 * @update_lock:
> >> +	 *
> >> +	 * update_lock is an internal backlight lock that serialise access
> >> +	 * to the update_status() method. The iupdate_lock mutex shall not be used
> >> +	 * by backlight drivers.
> >
> > In addition to the typo this directly contradicts the advice in the
> > original "Notes on locking".
> >
> > A change this dramatic needs to be fully explaining in the patch
> > description.
> >
> >
> > Daniel.
> >
> >
> >> +	 */
> >>  	struct mutex update_lock;
> >>  
> >> -	/* This protects the 'ops' field. If 'ops' is NULL, the driver that
> >> -	   registered this device has been unloaded, and if class_get_devdata()
> >> -	   points to something in the body of that driver, it is also invalid. */
> >> +	/**
> >> +	 * @ops_lock:
> >> +	 *
> >> +	 * ops_lock is an internal backlight lock that protects the ops pointer
> >> +	 * and is used around all accesses to ops and when the operations are
> >> +	 * invoked. The mutex shall not be used by backlight drivers.
> >> +	 */
> >>  	struct mutex ops_lock;
> >> +
> >> +	/**
> >> +	 * @ops:
> >> +	 *
> >> +	 * Pointer to the backlight operations. If ops is NULL, the driver that
> >> +	 * registered this device has been unloaded, and if class_get_devdata()
> >> +	 * points to something in the body of that driver, it is also invalid.
> >> +	 */
> >>  	const struct backlight_ops *ops;
> >>  
> >> -	/* The framebuffer notifier block */
> >> +	/**
> >> +	 * @fb_notif:
> >> +	 *
> >> +	 * The framebuffer notifier block
> >> +	 */
> >>  	struct notifier_block fb_notif;
> >>  
> >> -	/* list entry of all registered backlight devices */
> >> +	/**
> >> +	 * @entry:
> >> +	 *
> >> +	 * List entry of all registered backlight devices
> >> +	 */
> >>  	struct list_head entry;
> >>  
> >> +	/**
> >> +	 * @dev:
> >> +	 *
> >> +	 * Parent device.
> >> +	 */
> >>  	struct device dev;
> >>  
> >> -	/* Multiple framebuffers may share one backlight device */
> >> +	/**
> >> +	 * @fb_bl_on:
> >> +	 *
> >> +	 * Multiple fbdev's may share one backlight device. The fb_bl_on
> >> +	 * records the state of the individual fbdev.
> >> +	 */
> >>  	bool fb_bl_on[FB_MAX];
> >>  
> >> +	/**
> >> +	 * @use_count:
> >> +	 *
> >> +	 * The number of uses of fb_bl_on.
> >> +	 */
> >>  	int use_count;
> >>  };
> >>  
> >> -- 
> >> 2.25.1
> >> 
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center
diff mbox series

Patch

diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index 7f9cef299d6e..e2d72936bf05 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -14,21 +14,6 @@ 
 #include <linux/mutex.h>
 #include <linux/notifier.h>
 
-/* Notes on locking:
- *
- * backlight_device->ops_lock is an internal backlight lock protecting the
- * ops pointer and no code outside the core should need to touch it.
- *
- * Access to update_status() is serialised by the update_lock mutex since
- * most drivers seem to need this and historically get it wrong.
- *
- * Most drivers don't need locking on their get_brightness() method.
- * If yours does, you need to implement it in the driver. You can use the
- * update_lock mutex if appropriate.
- *
- * Any other use of the locks below is probably wrong.
- */
-
 enum backlight_update_reason {
 	BACKLIGHT_UPDATE_HOTKEY,
 	BACKLIGHT_UPDATE_SYSFS,
@@ -221,30 +206,80 @@  struct backlight_properties {
 	enum backlight_scale scale;
 };
 
+/**
+ * struct backlight_device - backlight device data
+ *
+ * This structure holds all data required by a backlight device.
+ */
 struct backlight_device {
-	/* Backlight properties */
+	/**
+	 * @props:
+	 *
+	 * Backlight properties
+	 */
 	struct backlight_properties props;
 
-	/* Serialise access to update_status method */
+	/**
+	 * @update_lock:
+	 *
+	 * update_lock is an internal backlight lock that serialise access
+	 * to the update_status() method. The iupdate_lock mutex shall not be used
+	 * by backlight drivers.
+	 */
 	struct mutex update_lock;
 
-	/* This protects the 'ops' field. If 'ops' is NULL, the driver that
-	   registered this device has been unloaded, and if class_get_devdata()
-	   points to something in the body of that driver, it is also invalid. */
+	/**
+	 * @ops_lock:
+	 *
+	 * ops_lock is an internal backlight lock that protects the ops pointer
+	 * and is used around all accesses to ops and when the operations are
+	 * invoked. The mutex shall not be used by backlight drivers.
+	 */
 	struct mutex ops_lock;
+
+	/**
+	 * @ops:
+	 *
+	 * Pointer to the backlight operations. If ops is NULL, the driver that
+	 * registered this device has been unloaded, and if class_get_devdata()
+	 * points to something in the body of that driver, it is also invalid.
+	 */
 	const struct backlight_ops *ops;
 
-	/* The framebuffer notifier block */
+	/**
+	 * @fb_notif:
+	 *
+	 * The framebuffer notifier block
+	 */
 	struct notifier_block fb_notif;
 
-	/* list entry of all registered backlight devices */
+	/**
+	 * @entry:
+	 *
+	 * List entry of all registered backlight devices
+	 */
 	struct list_head entry;
 
+	/**
+	 * @dev:
+	 *
+	 * Parent device.
+	 */
 	struct device dev;
 
-	/* Multiple framebuffers may share one backlight device */
+	/**
+	 * @fb_bl_on:
+	 *
+	 * Multiple fbdev's may share one backlight device. The fb_bl_on
+	 * records the state of the individual fbdev.
+	 */
 	bool fb_bl_on[FB_MAX];
 
+	/**
+	 * @use_count:
+	 *
+	 * The number of uses of fb_bl_on.
+	 */
 	int use_count;
 };