Commit 8bff57a938e92dfc8729e40f7aa9ad9a96262131 introduces a regression on this Dell C640 Radeon mobility 7500 laptop stopping the backlight from functioning.
Neither the hotkeys on the keyboard or the libsmbios utilities work on further commits.
I think something else is at play here as we do not change the bios scratch registers at all in the current driver. Perhaps an issue with radeonfb (if you are using it) or acpi in your kernel?
I'm not using radeonfb and I identified this commit by doing a git bisect. Nothing else changed in the system.
I examined the offending commit a little bit more and found out that bringing back this line made the backlight come on again:
save->bios_5_scratch = orig->bios_5_scratch;
(In reply to comment #3)
> I examined the offending commit a little bit more and found out that bringing
> back this line made the backlight come on again:
> save->bios_5_scratch = orig->bios_5_scratch;
Sorry, I didn't realize that there were two instances of this expression.
I meant the one at line ~6501 when at commit 8bff57a938e92dfc8729e40f7aa9ad9a96262131
Verified, thanks a bunch!