Re: [PATCH]Panasonic Hotkey Driver v0.5 [2/2]

[Nate Lawson <nate-Y6VGUYTwhu0@public.gmane.org>]

David Bronaugh wrote:
> Hiroshi Miura wrote:
>> It's from Panasonic spec.
>>
>> 0,n  -- brightness on AC 1,n  -- brightness on battery.
>> If pc go suspend/resume, BIOS set brightness according to this value.
>>
>> I should further study this interface.
>>
> At least on my R1, this function is incorrect. Brightness values range 
> from 0-255 on my R1. Setting field 4 and field 7 of sinf have exactly 
> the same effect (it would appear that they map to the same function) 
> even though they end up storing different values; disconnecting and 
> connecting AC power does not change how bright the screen is at all. I 
> believe this is intentional; however, I also believe that using ACPI to 
> store values like this is pointless and it would be better to simplify 
> the interface.
> 
> My experience is that changing the code to accept values from 0-255 
> allows me to set the full range of screen brightnesses; however, setting 
> values less than 11 makes the screen flicker like crazy (I assume this 
> is because I am underpowering the backlight). So perhaps a floor of, 
> say, 15 on the screen brightness would be a good choice to avoid problems.
> 
> Also a small complaint -- displaying all 6 registers in 
> acpi_pcc_read_brightness is confusing (not to me since I understand the 
> code, but to end users).

We handle these different laptops correctly in the FreeBSD 
acpi_panasonic driver.  It may be a good example for you.

-- 
Nate


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