drm/i915: Ensure the HW is powered when accessing the CRC HW block

The assumption when adding the intel_display_power_is_enabled() checks
was that if it returns success the power can't be turned off afterwards
during the HW access, which is guaranteed by modeset locks. This isn't
always true, so make sure we hold a dedicated reference for the time of
the access.

While at it also add the missing reference around the HW access in
i915_interrupt_info().

v2:
- update the commit message mentioning that this also fixes the
  HW access in the interrupt info debugfs entry (Daniel)

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1455296121-4742-9-git-send-email-imre.deak@intel.com
(cherry picked from commit e129649b7a3e1d50d196e159492496777769437e)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 0fc38bb..cf39ed3 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -825,8 +825,11 @@
 		}
 
 		for_each_pipe(dev_priv, pipe) {
-			if (!intel_display_power_is_enabled(dev_priv,
-						POWER_DOMAIN_PIPE(pipe))) {
+			enum intel_display_power_domain power_domain;
+
+			power_domain = POWER_DOMAIN_PIPE(pipe);
+			if (!intel_display_power_get_if_enabled(dev_priv,
+								power_domain)) {
 				seq_printf(m, "Pipe %c power disabled\n",
 					   pipe_name(pipe));
 				continue;
@@ -840,6 +843,8 @@
 			seq_printf(m, "Pipe %c IER:\t%08x\n",
 				   pipe_name(pipe),
 				   I915_READ(GEN8_DE_PIPE_IER(pipe)));
+
+			intel_display_power_put(dev_priv, power_domain);
 		}
 
 		seq_printf(m, "Display Engine port interrupt mask:\t%08x\n",
@@ -3985,6 +3990,7 @@
 	struct intel_pipe_crc *pipe_crc = &dev_priv->pipe_crc[pipe];
 	struct intel_crtc *crtc = to_intel_crtc(intel_get_crtc_for_pipe(dev,
 									pipe));
+	enum intel_display_power_domain power_domain;
 	u32 val = 0; /* shut up gcc */
 	int ret;
 
@@ -3995,7 +4001,8 @@
 	if (pipe_crc->source && source)
 		return -EINVAL;
 
-	if (!intel_display_power_is_enabled(dev_priv, POWER_DOMAIN_PIPE(pipe))) {
+	power_domain = POWER_DOMAIN_PIPE(pipe);
+	if (!intel_display_power_get_if_enabled(dev_priv, power_domain)) {
 		DRM_DEBUG_KMS("Trying to capture CRC while pipe is off\n");
 		return -EIO;
 	}
@@ -4012,7 +4019,7 @@
 		ret = ivb_pipe_crc_ctl_reg(dev, pipe, &source, &val);
 
 	if (ret != 0)
-		return ret;
+		goto out;
 
 	/* none -> real source transition */
 	if (source) {
@@ -4024,8 +4031,10 @@
 		entries = kcalloc(INTEL_PIPE_CRC_ENTRIES_NR,
 				  sizeof(pipe_crc->entries[0]),
 				  GFP_KERNEL);
-		if (!entries)
-			return -ENOMEM;
+		if (!entries) {
+			ret = -ENOMEM;
+			goto out;
+		}
 
 		/*
 		 * When IPS gets enabled, the pipe CRC changes. Since IPS gets
@@ -4081,7 +4090,12 @@
 		hsw_enable_ips(crtc);
 	}
 
-	return 0;
+	ret = 0;
+
+out:
+	intel_display_power_put(dev_priv, power_domain);
+
+	return ret;
 }
 
 /*