drm/i915: Markup paired operations on display power domains

The majority of runtime-pm operations are bounded and scoped within a
function; these are easy to verify that the wakeref are handled
correctly. We can employ the compiler to help us, and reduce the number
of wakerefs tracked when debugging, by passing around cookies provided
by the various rpm_get functions to their rpm_put counterpart. This
makes the pairing explicit, and given the required wakeref cookie the
compiler can verify that we pass an initialised value to the rpm_put
(quite handy for double checking error paths).

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190114142129.24398-16-chris@chris-wilson.co.uk

1 files changed, 20 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/intel_csr.c b/drivers/gpu/drm/i915/intel_csr.c
index a516697bf57d..ea5fb64d33dd 100644
--- a/drivers/gpu/drm/i915/intel_csr.c
+++ b/drivers/gpu/drm/i915/intel_csr.c
@@ -409,6 +409,21 @@ static uint32_t *parse_csr_fw(struct drm_i915_private *dev_priv,
 	return memcpy(dmc_payload, &fw->data[readcount], nbytes);
 }
 
+static void intel_csr_runtime_pm_get(struct drm_i915_private *dev_priv)
+{
+	WARN_ON(dev_priv->csr.wakeref);
+	dev_priv->csr.wakeref =
+		intel_display_power_get(dev_priv, POWER_DOMAIN_INIT);
+}
+
+static void intel_csr_runtime_pm_put(struct drm_i915_private *dev_priv)
+{
+	intel_wakeref_t wakeref __maybe_unused =
+		fetch_and_zero(&dev_priv->csr.wakeref);
+
+	intel_display_power_put(dev_priv, POWER_DOMAIN_INIT, wakeref);
+}
+
 static void csr_load_work_fn(struct work_struct *work)
 {
 	struct drm_i915_private *dev_priv;
@@ -424,8 +439,7 @@ static void csr_load_work_fn(struct work_struct *work)
 
 	if (dev_priv->csr.dmc_payload) {
 		intel_csr_load_program(dev_priv);
-
-		intel_display_power_put(dev_priv, POWER_DOMAIN_INIT);
+		intel_csr_runtime_pm_put(dev_priv);
 
 		DRM_INFO("Finished loading DMC firmware %s (v%u.%u)\n",
 			 dev_priv->csr.fw_path,
@@ -467,7 +481,7 @@ void intel_csr_ucode_init(struct drm_i915_private *dev_priv)
 	 * suspend as runtime suspend *requires* a working CSR for whatever
 	 * reason.
 	 */
-	intel_display_power_get(dev_priv, POWER_DOMAIN_INIT);
+	intel_csr_runtime_pm_get(dev_priv);
 
 	if (INTEL_GEN(dev_priv) >= 12) {
 		/* Allow to load fw via parameter using the last known size */
@@ -538,7 +552,7 @@ void intel_csr_ucode_suspend(struct drm_i915_private *dev_priv)
 
 	/* Drop the reference held in case DMC isn't loaded. */
 	if (!dev_priv->csr.dmc_payload)
-		intel_display_power_put(dev_priv, POWER_DOMAIN_INIT);
+		intel_csr_runtime_pm_put(dev_priv);
 }
 
 /**
@@ -558,7 +572,7 @@ void intel_csr_ucode_resume(struct drm_i915_private *dev_priv)
 	 * loaded.
 	 */
 	if (!dev_priv->csr.dmc_payload)
-		intel_display_power_get(dev_priv, POWER_DOMAIN_INIT);
+		intel_csr_runtime_pm_get(dev_priv);
 }
 
 /**
@@ -574,6 +588,7 @@ void intel_csr_ucode_fini(struct drm_i915_private *dev_priv)
 		return;
 
 	intel_csr_ucode_suspend(dev_priv);
+	WARN_ON(dev_priv->csr.wakeref);
 
 	kfree(dev_priv->csr.dmc_payload);
 }