[Intel-gfx] drm/i915: don't change DRM configuration when releasing load detect pipe

[Eric Anholt]

On Thu, 18 Feb 2010 14:51:54 -0800, Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
> When we get a CRTC to use for load detection, we restore its DPMS state
> if needed.  We shouldn't, however, change the DRM configuration by
> calling drm_helper_disable_unused_functions when we release the CRTC.
> Doing so can cause problems with resume, since at suspend or lid close
> time, X may choose to probe outputs.  If it doesn't re-probe them at
> open or resume time, LVDS won't be restored, since
> drm_helper_disable_unused_functions will have turned it off, preventing
> the mode set at lid open from restoring it.

It seems to me like the bug is that drm_helper_disable_unused_functions
whacks the configuration.  Why should it do that?

		if (connector->status == connector_status_disconnected)
			connector->encoder = NULL;

This function back in UMS used to be about getting the system from
unknown bootup state to other junk being turned off after the initial
modeset (which was of course broken, since having the other junk turned
on during modeset could break things, so really it should have been
intel_turn_everything_off_thanks() before doing a modeset).

Once that's fixed, it seems like it'd be a replacement for the
turn-off-after-load-detect logic in the load detect pipe release
function.
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