While we currently grab a runtime PM ref in nouveau's normal connector
detection code, we apparently don't do this for MST. This means if we're
in a scenario where the GPU is suspended and userspace attempts to do a
connector probe on an MSTC connector, the probe will fail entirely due
to the DP aux channel and GPU not being woken up:

[  316.633489] nouveau 0000:01:00.0: i2c: aux 000a: begin idle timeout ffffffff
[  316.635713] nouveau 0000:01:00.0: i2c: aux 000a: begin idle timeout ffffffff
[  316.637785] nouveau 0000:01:00.0: i2c: aux 000a: begin idle timeout ffffffff
...

So, grab a runtime PM ref here.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

Messed up when sending pull request and sent an outdated version of
previous patch, this fixes it up to remove warnings.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

Fixes eDP backlight issues on more recent laptops.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

If a HPD pulse signalling the need to retrain the link occurs between
the KMS driver releasing the output and the supervisor interrupt that
finishes the teardown, it was possible get a NULL-ptr deref.

Avoid this by marking the link as inactive earlier.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

We need to do this earlier to prevent aux channel timeouts in resume
paths on certain systems.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

This Falcon application doesn't appear to be present on some newer
systems, so let's not fail init if we can't find it.

TBD: is there a way to determine whether it *should* be there?

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

Fixes oopses in certain failure paths.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

The NV_ERROR macro requires drm->client to be initialised, which it may not
be at this stage of the init process.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

It looks like that when we moved over to using
drm_connector_for_each_possible_encoder() in nouveau, that one rather
important part of this function got dropped by accident:

	/*          Right   v   here */
	for (i = 0; nv_encoder = NULL, i < DRM_CONNECTOR_MAX_ENCODER; i++) {
		int id = connector->encoder_ids[i];
		if (id == 0)
			break;

Since it's rather difficult to notice: the conditional in this loop is
actually:

	nv_encoder = NULL, i < DRM_CONNECTOR_MAX_ENCODER

Meaning that all early breaks result in nv_encoder keeping it's value,
otherwise nv_encoder = NULL. Ugh.

Since this got dropped, nouveau_connector_ddc_detect() now returns an
encoder for every single connector, regardless of whether or not it's
detected:

    [ 1780.056185] nouveau 0000:01:00.0: DRM: DDC responded, but no EDID for DP-2

So: fix this to ensure we only return an encoder if we actually found
one, and clean up the rest of the function while we're at it since it's
nearly impossible to read properly.

Changes since v1:
- Don't skip ddc probing for LVDS if we can't switch DDC through
  vga-switcheroo, just do the DDC probing without calling
  vga_switcheroo_lock_ddc() - skeggsb

Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Fixes: ddba766dd07e ("drm/nouveau: Use drm_connector_for_each_possible_encoder()")
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>