Sadly, it does appear to exist upstream as well - tested with 3.9.0-030900rc4.201303232035 from that directory. Mainline kernel behaviour is the same: fresh from boot, both the hotkeys and the applet change the brightness OK; after suspend and resume, the laptop comes back but the backlight is off and the hotkeys can't turn it up.
Unfortunately, this makes the laptop unusable in Ubuntu for my purposes. However, I can boot back into Ubuntu if there are further tests to do to work on this one.
Sadly, it does appear to exist upstream as well - tested with 3.9.0-030900rc4 .201303232035 from that directory. Mainline kernel behaviour is the same: fresh from boot, both the hotkeys and the applet change the brightness OK; after suspend and resume, the laptop comes back but the backlight is off and the hotkeys can't turn it up.
Unfortunately, this makes the laptop unusable in Ubuntu for my purposes. However, I can boot back into Ubuntu if there are further tests to do to work on this one.