I have a Dell Inspiron e1405, and I just upgraded it to the latest BIOS
version, A05. It went well (Dell has a Linux BIOS bootdisk
tool that can create a physical floppy or a bootable kernel + ramdisk
for GRUB that will update your BIOS!), but I found that when I loaded
the video kernel module, which implements ACPI Video support,
the brightness hotkeys stopped working.
I eventually tracked the problem down to the following pieces of code:
#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
and
static int
acpi_video_get_next_level(struct acpi_video_device *device,
u32 level_current, u32 event)
{
/*Fix me */
return level_current;
}
both in drivers/acpi/video.c. Basically, acpi_video_get_next_level is
supposed to take the current brightness level and the ACPI video event
number as parameters, and return the next brightness level that should be
used, but nobody implemented it.
So I did. Here's the patch:
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
* Copyright (C) 2004 Bruno Ducrot
+ * Copyright (C) 2006 Thomas Tuttle
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
@@ -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
I've submitted it to all the mailing lists I can find, so it should
be in the kernel eventually. It works on my laptop, but I imagine few
others actually use ACPI video hotkey events if nobody's bothered to
implement them fully yet.
