[Intel-gfx] [PATCH 2/2] drm/i915: fixup load-detect on enabled, but not active pipe

Chris Wilson chris at chris-wilson.co.uk
Fri Apr 20 21:44:59 CEST 2012

On Fri, 20 Apr 2012 21:03:36 +0200, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> Somehow we have a fast-path that tries to avoid going through
> the load-detect code when the encode already has a crtc associated.
> But this fails horribly when the crtc is off. The load detect pipe
> itself manages this case well (and also does not forget to restore the
> dpms state), so just rip out this special case.
> The issue seems to go back all the way to the commit that originally
> introduced load-detection on the vga output:
> commit e4a5d54f924ea5ce2913d9d0687d034004816465
> Author: Ma Ling <ling.ma at intel.com>
> Date:   Tue May 26 11:31:00 2009 +0800
>     drm/i915: Add support for VGA load detection (pre-945).
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=43020
> Reported-by: Jean Delvare <khali at linux-fr.org>
> Signed-Off-by: Daniel Vetter <daniel.vetter at ffwll.ch>

I'm happy that intel_get_load_detect_pipe() does the right thing if the
connector is already active (so that we don't blank an active display
when checking for disconnections). I was worried that this meant we had
a deeper bug with our connection state, but as Daniel made me realise it
is that the "fast path" is lacking the enable.

For this and subsuquent TV fix, begone foul code,
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

Chris Wilson, Intel Open Source Technology Centre

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