[Intel-gfx] [PATCH] drm/i915: no LVDS on Intel SandyBridge SDVs

[Chris Wilson]

On Tue, 21 Dec 2010 10:14:51 -0800, Keith Packard <keithp at keithp.com> wrote:
> On Tue, 21 Dec 2010 11:36:44 +0000, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> 
> > I think once upon a time I found a reliable method in the docs:
> > intel_lvds_ddc_probe(). However that only seemed to work over GMBUS...
> 
> That probably depends on the panel having DDC, which many don't, right?
> Maybe we can assume the SDV panels do?

The test we do is simply whether the LVDS i2c pins are addressable. That
requires differentiating between an IO error and a NAK, which at present
is only possible using GMBUS. The reference to this method I found in the
BIOS writers' guide, but of course that doesn't actually explain how it
works (especially the significance of address 0xa0).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre