Hi Thomas,
Please check if the attached patch helps?
Regards,
Alex.
Thomas Bächler wrote:
> Hello,
>
> After doing some research myself, I thought it was time to refer to this
> list for advice. I am using a Lenovo 3000 N100 running Linux 2.6.23-rc4
> (x86_64). After loading the video kernel module, I can change the
> brightness of my display between 0 and 100 by cat $level >
> /sys/class/backlight/acpi_video0/brightness.
>
> However, when using the brightness keys on my keyboard, I can decrease
> the brightness until 0, but I can never increase it over 42 again.
>
> I looked into the code and inserted a printk into the
> acpi_video_get_next_level() function to print the min, max,
> level_current, min_above and max_below values when I press the keys, as
> well as the list of available levels. This is what I got:
>
> available levels: 100 57 0 14 28 43 57 71 86 100
> Pressing the decrease button:
> min: 0, max: 100, level_current: 98, min_above: 100, max_below: 86
> min: 0, max: 100, level_current: 84, min_above: 86, max_below: 71
> min: 0, max: 100, level_current: 70, min_above: 71, max_below: 57
> min: 0, max: 100, level_current: 56, min_above: 57, max_below: 43
> min: 0, max: 100, level_current: 42, min_above: 43, max_below: 28
> min: 0, max: 100, level_current: 28, min_above: 43, max_below: 14
> min: 0, max: 100, level_current: 14, min_above: 28, max_below: 0
> Pressing the increase button:
> min: 0, max: 100, level_current: 0, min_above: 14, max_below: 0
> min: 0, max: 100, level_current: 14, min_above: 28, max_below: 0
> min: 0, max: 100, level_current: 28, min_above: 43, max_below: 14
> min: 0, max: 100, level_current: 42, min_above: 43, max_below: 28
> min: 0, max: 100, level_current: 42, min_above: 43, max_below: 28
> min: 0, max: 100, level_current: 42, min_above: 43, max_below: 28
>
> It seems like Linux thinks that the level 43 is supported (maybe because
> my bios reported just that), but when it tries to set it to 43, it is
> actually set to 42. The same seems to be the case for the other levels
> above 43 as well.
>
> As I don't know anything about ACPI, I am stuck here. Any help would be
> appreciated.
>
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ACPI: VIDEO: Adjust current level to closest available one.
From: Alexey Starikovskiy <astarikovskiy@xxxxxxx>
Signed-off-by: Alexey Starikovskiy <astarikovskiy@xxxxxxx>
---
drivers/acpi/video.c | 13 ++++++++++++-
1 files changed, 12 insertions(+), 1 deletions(-)
diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 3c9bb85..63b1101 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -1634,9 +1634,20 @@ static int
acpi_video_get_next_level(struct acpi_video_device *device,
u32 level_current, u32 event)
{
- int min, max, min_above, max_below, i, l;
+ int min, max, min_above, max_below, i, l, delta = 255;
max = max_below = 0;
min = min_above = 255;
+ /* Find closest level to level_current */
+ for (i = 0; i < device->brightness->count; i++) {
+ l = device->brightness->levels[i];
+ if (abs(l - level_current) < abs(delta)) {
+ delta = l - level_current;
+ if (!delta)
+ break;
+ }
+ }
+ /* Ajust level_current to closest available level */
+ level_current += delta;
for (i = 0; i < device->brightness->count; i++) {
l = device->brightness->levels[i];
if (l < min)
