[PATCH] backlight: Backlight Class Improvements

Backlight class attributes are currently easy to implement incorrectly.
Moving certain handling into the backlight core prevents this whilst at the
same time makes the drivers simpler and consistent.  The following changes are
included:

The brightness attribute only sets and reads the brightness variable in the
backlight_properties structure.

The power attribute only sets and reads the power variable in the
backlight_properties structure.

Any framebuffer blanking events change a variable fb_blank in the
backlight_properties structure.

The backlight driver has only two functions to implement.  One function is
called when any of the above properties change (to update the backlight
brightness), the second is called to return the current backlight brightness
value.  A new attribute "actual_brightness" is added to return this brightness
as determined by the driver having combined all the above factors (and any
driver/device specific factors).

Additionally, the backlight core takes care of checking the maximum brightness
is not exceeded and of turning off the backlight before device removal.

The corgi backlight driver is updated to reflect these changes.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 15 insertions, 10 deletions

diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index bb9e54322322..75e91f5b6a04 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -19,20 +19,25 @@ struct fb_info;
 struct backlight_properties {
         /* Owner module */
         struct module *owner;
-        /* Get the backlight power status (0: full on, 1..3: power saving
-           modes; 4: full off), see FB_BLANK_XXX */
-        int (*get_power)(struct backlight_device *);
-        /* Enable or disable power to the LCD (0: on; 4: off, see FB_BLANK_XXX) */
-        int (*set_power)(struct backlight_device *, int power);
-        /* Maximal value for brightness (read-only) */
-        int max_brightness;
-        /* Get current backlight brightness */
+
+        /* Notify the backlight driver some property has changed */
+        int (*update_status)(struct backlight_device *);
+        /* Return the current backlight brightness (accounting for power,
+           fb_blank etc.) */
         int (*get_brightness)(struct backlight_device *);
-        /* Set backlight brightness (0..max_brightness) */
-        int (*set_brightness)(struct backlight_device *, int brightness);
         /* 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 fb_info *);
+
+        /* Current User requested brightness (0 - max_brightness) */
+        int brightness;
+        /* Maximal value for brightness (read-only) */
+        int max_brightness;
+        /* Current FB Power mode (0: full on, 1..3: power saving
+           modes; 4: full off), see FB_BLANK_XXX */
+        int power;
+        /* FB Blanking active? (values as for power) */
+        int fb_blank;
 };
 
 struct backlight_device {