[Intel-gfx] [PATCH 1/2] drm/i915: check whether we actually received an edid in detect_ddc

[Chris Wilson]

On Wed, 11 Jul 2012 12:31:52 +0200, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> Somehow detect_ddc manages to fall through all checks when we think
> that something responds on the ddc i2c address, but the edid read
> failed. Fix this up by explicitly checking for this case.
> 
> This fixes a regression on newer chips because since
> 
> commit aaa377302b2994fcc2c66741b47da33feb489dca
> Author: Daniel Vetter <daniel.vetter at ffwll.ch>
> Date:   Sat Jun 16 15:30:32 2012 +0200
> 
>     drm/i915/crt: Do not rely upon the HPD presence pin
> 
> we use ddc detection also on hotplug capable platforms. And one of
> these reads all 0s for any i2c transaction if nothing is connected to
> the vga port.
> 
> v2: Implement Chris Wilson's review:
> - simplify logic, default to "nothing detected"
> - kill stale comment
> - BUG_ON(!crt->type != ANALOG)
> 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=51900
> Tested-by: Yang Guang <guang.a.yang at intel.com>
> Signed-Off-by: Daniel Vetter <daniel.vetter at ffwll.ch>

I'm happy with that, and thanks for the extra clarification in the debug
messages.
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre