* Melchior FRANZ -- Tuesday 26 April 2011:
I've replied to this error message, but here again for this audience: The commit that broke all 2.6.38.* releases for my machine is this: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdif... (Takashi Iwai: "drm/i915: Revive combination mode for backlight control").
In 'is_backlight_combination_mode()' INTEL_INFO(dev)->gen equals 4, and the function returns 0x40000000 in "combination mode". In 'intel_panel_get_backlight()' this happens:
val = I915_READ(BLC_PWM_CTL) & BACKLIGHT_DUTY_CYCLE_MASK; // val = 0x0b4a if (IS_PINEVIEW(dev)) // false val >>= 1;
if (is_backlight_combination_mode(dev)){ u8 lbpc;
val &= ~1; // val = 0x0b4a pci_read_config_byte(dev->pdev, PCI_LBPC, &lbpc); // lbpc = 0 val *= lbpc; // val = 0 }
The backlight remains off and does also not react to the "brighter" key event.
Reverting the patch fixes my system, obviously.
m.