drm/i915: add POWER_DOMAIN_PLLS

And get/put it when needed. The special thing about this commit is
that it will now return false in ibx_pch_dpll_get_hw_state() in case
the power domain is not enabled. This will fix some WARNs we have when
we run pm_rpm on SNB.

Testcase: igt/pm_rpm
Bugzilla:https://bugs.freedesktop.org/show_bug.cgi?id=80463
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0874f35..d61c5e4 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1814,6 +1814,8 @@
 	}
 	WARN_ON(pll->on);
 
+	intel_display_power_get(dev_priv, POWER_DOMAIN_PLLS);
+
 	DRM_DEBUG_KMS("enabling %s\n", pll->name);
 	pll->enable(dev_priv, pll);
 	pll->on = true;
@@ -1850,6 +1852,8 @@
 	DRM_DEBUG_KMS("disabling %s\n", pll->name);
 	pll->disable(dev_priv, pll);
 	pll->on = false;
+
+	intel_display_power_put(dev_priv, POWER_DOMAIN_PLLS);
 }
 
 static void ironlake_enable_pch_transcoder(struct drm_i915_private *dev_priv,
@@ -11302,6 +11306,9 @@
 {
 	uint32_t val;
 
+	if (!intel_display_power_enabled(dev_priv, POWER_DOMAIN_PLLS))
+		return false;
+
 	val = I915_READ(PCH_DPLL(pll->id));
 	hw_state->dpll = val;
 	hw_state->fp0 = I915_READ(PCH_FP0(pll->id));
@@ -12867,6 +12874,9 @@
 
 		DRM_DEBUG_KMS("%s hw state readout: refcount %i, on %i\n",
 			      pll->name, pll->refcount, pll->on);
+
+		if (pll->refcount)
+			intel_display_power_get(dev_priv, POWER_DOMAIN_PLLS);
 	}
 
 	list_for_each_entry(encoder, &dev->mode_config.encoder_list,