On Mon, Oct 14, 2019 at 11:00:57PM +0200, Mark Kettenis wrote: > > Date: Sun, 13 Oct 2019 21:37:53 -0500 > > From: joshua stein <[email protected]> > > > > Newer ThinkPads have ACPI goo to allow acpivout to control screen > > backlight, so don't take over ws_[gs]et_param from it. This allows > > for 100 levels of backlight control rather than the 10 or 15 that > > are supported through acpithinkpad using its proprietary ACPI or > > CMOS interfaces. > > > > You can see the difference with and without this patch by doing: > > > > xbacklight -set 1 -steps 100 > > xbacklight -set 100 -steps 100 > > > > Apparently this will also be needed for newer AMD ThinkPads that use > > radeondrm. > > > > "Newer" here is being defined as anything not reporting version 1 > > (THINKPAD_HKEY_VERSION1) of the ThinkPad ACPI interface. > > Note that -current reports the version number in dmesg. For now > you'll need to compile your own kernel though, since there won't be > any new snapshots until 6.6 is released. > > > For responding to hardware brightness keys, you'll want to test with > > the acpivout patch I posted since otherwise the keys will be > > adjusting the backlight by 1% each time, and it may seem like it's > > not doing anything. That patch makes it properly adjust by 5% each > > time (but you still get fine-grained changes through wsconsctl or > > xbacklight). > > Wo what we need to get tested is whether backlight control (stil) > works on machines that report: > > acpithinkpad0 at acpi0: version 2.0 > > My x1c3 reports version 1.0 so I suspect the x250/t450/t550 reports > that as well (but it would be goo to get that confirmed). So we're > primarily interested in later generations.
My x280 reports version 2.0 and this feels like a great improvement.
