[PATCH] Implementation of acpi_video_get_next_level

[Thomas Tuttle <linux-kernel@ttuttle.net>]

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PATCH: Implementation of acpi_video_get_level

(patch file attached)

acpi_video_get_next_level was supposed to implement an algorithm to
select a new brightness level based on the old brightness level of an
ACPI video device, but it simply says "/* Fix me */" and returns the
current brightness.

This patch implements acpi_video_get_next_level properly.  It had to
change a few constants at the top of the file because they were
(apparently) wrong, but it appears to work on my Dell Inspiron e1405
(with BIOS A05 only--BIOS A04 doesn't seem to send ACPI video hotkey
events).

I'm sending this to Len Brown, the linux-kernel and linux-acpi lists at
kernel.org, the acpi-devel list at Sourceforge, and the linux-acpi alias
at Intel.  I'm not sure who should be the one to apply it, but it's a
small and simple enough patch that it shouldn't require a complicated
review.

Thanks for your time, and hope this helps,

Thomas Tuttle

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diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 56666a9..2fc78ca 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -3,6 +3,7 @@
  *
  *  Copyright (C) 2004 Luming Yu <luming.yu@intel.com>
  *  Copyright (C) 2004 Bruno Ducrot <ducrot@poupinou.org>
+ *  Copyright (C) 2006 Thomas Tuttle <linux-kernel@ttuttle.net>
  *
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  *
@@ -47,11 +48,11 @@ #define ACPI_VIDEO_NOTIFY_CYCLE		0x82
 #define ACPI_VIDEO_NOTIFY_NEXT_OUTPUT	0x83
 #define ACPI_VIDEO_NOTIFY_PREV_OUTPUT	0x84
 
-#define ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS	0x82
-#define	ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS	0x83
-#define ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS	0x84
-#define ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS	0x85
-#define ACPI_VIDEO_NOTIFY_DISPLAY_OFF		0x86
+#define ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS	0x85
+#define	ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS	0x86
+#define ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS	0x87
+#define ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS	0x88
+#define ACPI_VIDEO_NOTIFY_DISPLAY_OFF		0x89
 
 #define ACPI_VIDEO_HEAD_INVALID		(~0u - 1)
 #define ACPI_VIDEO_HEAD_END		(~0u)
@@ -1509,8 +1510,30 @@ static int
 acpi_video_get_next_level(struct acpi_video_device *device,
 			  u32 level_current, u32 event)
 {
-	/*Fix me */
-	return level_current;
+	int min, max, min_above, max_below, i, l;
+	max = max_below = 0;
+	min = min_above = 255;
+	for (i = 0; i < device->brightness->count; i++) {
+		l = device->brightness->levels[i];
+		if (l < min) min = l;
+		if (l > max) max = l;
+		if (l < min_above && l > level_current) min_above = l;
+		if (l > max_below && l < level_current) max_below = l;
+	}
+
+	switch (event) {
+	case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS:
+		return (level_current < max) ? min_above : min;
+	case ACPI_VIDEO_NOTIFY_INC_BRIGHTNESS:
+		return (level_current < max) ? min_above : max;
+	case ACPI_VIDEO_NOTIFY_DEC_BRIGHTNESS:
+		return (level_current > min) ? max_below : min;
+	case ACPI_VIDEO_NOTIFY_ZERO_BRIGHTNESS:
+	case ACPI_VIDEO_NOTIFY_DISPLAY_OFF:
+		return 0;
+	default:
+		return level_current;
+	}
 }
 
 static void

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