[Intel-gfx] Thinkpad x220: GMBUS [i915 gmbus dpb] timed out, falling back to bit banging on pin 5

[Anton Blanchard]

Hi,

I have an x220 Thinkpad (42905AM) running the latest BIOS
(8DET67WW 1.37 12/05/2012). When running a checkout from a few days ago
(5af43c24ca59) the kernel complains about falling back to bit banging
mode:

[drm] Initialized drm 1.1.0 20060810
[drm] Memory usable by graphics device = 2048M
i915 0000:00:02.0: setting latency timer to 64
i915 0000:00:02.0: irq 40 for MSI/MSI-X
[drm] Supports vblank timestamp caching Rev 1 (10.10.2010).
[drm] Driver supports precise vblank timestamp query.
[drm] Wrong MCH_SSKPD value: 0x16040307
[drm] This can cause pipe underruns and display issues.
[drm] Please upgrade your BIOS to fix this.
fbcon: inteldrmfb (fb0) is primary device
i915 0000:00:02.0: fb0: inteldrmfb frame buffer device
i915 0000:00:02.0: registered panic notifier
[drm] Initialized i915 1.6.0 20080730 for 0000:00:02.0 on minor 0
[drm] Enabling RC6 states: RC6 on, RC6p off, RC6pp off 
[drm] GMBUS [i915 gmbus dpb] timed out, falling back to bit banging on
pin 5

I'm not sure if the bad MCH_SSKPD setting could be causing this.

Anton