sony_laptop: Default values for keyboard backlight

[Karol Babioch <karol@babioch.de>]

[-- Attachment #1: Type: text/plain, Size: 1701 bytes --]

Hi,

the keyboard backlight has been working for me for the last couple of
years without any problems and I was fine with the default values, so I
wasn't too happy when I realized that a recent kernel upgrade has
changed this by leaving the backlight always on.

I've tracked down the "issue" to a specific commit (see [1]) from Mattia
itself, so I guess he had every reason to make this change. I've dealt
with the "problem" with a specific modprobe.d file.

I'm wondering whether this is the right approach, though. The default
behavior before even any "sony-laptop" module is loaded at all (e.g.
within the BIOS and/or the bootloader selection menu) is to enable the
keyboard backlight with a timeout of 10 seconds - at least on my machine.

This has changed with the recent commit once the module is actually
loaded and the backlight is never turned off again. The sysfs interface
reports "-1" for both "kbd_backlight" and "kbd_backlight_timeout", which
in itself is fine according to the message describing the commit as the
values can't be known until having them set for the first time.

But to my understanding the commit shouldn't change the default behavior
for the keyboard backlight itself, as it actually doesn't touch the
registers involved. But as the behavior has actually changed, something
is definitely going on here, which might not necessarily be intentional.

So is this something that has been overlooked, or is my understanding of
the new behavior wrong?

Best regards,
Karol Babioch

[1]:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/platform/x86/sony-laptop.c?id=294d31e8227c9892a89d6b3e58d17886b79ea4e6


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 836 bytes --]