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.
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).
Index: sys/dev/acpi/acpithinkpad.c
===================================================================
RCS file: /cvs/src/sys/dev/acpi/acpithinkpad.c,v
retrieving revision 1.66
diff -u -p -u -p -r1.66 acpithinkpad.c
--- sys/dev/acpi/acpithinkpad.c 13 Oct 2019 10:56:31 -0000 1.66
+++ sys/dev/acpi/acpithinkpad.c 14 Oct 2019 02:28:57 -0000
@@ -320,8 +320,10 @@ thinkpad_attach(struct device *parent, s
wskbd_set_backlight = thinkpad_set_kbd_backlight;
}
- if (aml_evalinteger(sc->sc_acpi, sc->sc_devnode, "PBLG",
- 0, NULL, &sc->sc_brightness) == 0) {
+ /* On version 2 and newer, let *drm or acpivout control brightness */
+ if (sc->sc_hkey_version == THINKPAD_HKEY_VERSION1 &&
+ (aml_evalinteger(sc->sc_acpi, sc->sc_devnode, "PBLG",
+ 0, NULL, &sc->sc_brightness) == 0)) {
ws_get_param = thinkpad_get_param;
ws_set_param = thinkpad_set_param;
}
