drm/i915: Stop sleeping from inside gen6_bsd_submit_request()

submit_request() is called from an atomic context, it's not allowed to
sleep. We have to be careful in our parameters to
intel_uncore_wait_for_register() to limit ourselves to the atomic wait
loop and not incur the wrath of our warnings.

Fixes: 6976e74b5fa1 ("drm/i915: Don't allow overuse of __intel_wait_for_register_fw()")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170410143807.22725-1-chris@chris-wilson.co.uk
Link: http://patchwork.freedesktop.org/patch/msgid/20170411101340.31994-2-chris@chris-wilson.co.uk
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -1729,11 +1729,11 @@ static void gen6_bsd_submit_request(struct drm_i915_gem_request *request)
 	I915_WRITE64_FW(GEN6_BSD_RNCID, 0x0);
 
 	/* Wait for the ring not to be idle, i.e. for it to wake up. */
-	if (intel_wait_for_register_fw(dev_priv,
-				       GEN6_BSD_SLEEP_PSMI_CONTROL,
-				       GEN6_BSD_SLEEP_INDICATOR,
-				       0,
-				       50))
+	if (__intel_wait_for_register_fw(dev_priv,
+					 GEN6_BSD_SLEEP_PSMI_CONTROL,
+					 GEN6_BSD_SLEEP_INDICATOR,
+					 0,
+					 1000, 0, NULL))
 		DRM_ERROR("timed out waiting for the BSD ring to wake up\n");
 
 	/* Now that the ring is fully powered up, update the tail */