drm/i915: clarify comment about mandatory RPM put/get during driver load/unload
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450203038-5150-2-git-send-email-imre.deak@intel.com
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index 2c2151f..9945040 100644
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -1975,9 +1975,15 @@
*/
void intel_power_domains_fini(struct drm_i915_private *dev_priv)
{
- /* The i915.ko module is still not prepared to be loaded when
+ /*
+ * The i915.ko module is still not prepared to be loaded when
* the power well is not enabled, so just enable it in case
- * we're going to unload/reload. */
+ * we're going to unload/reload.
+ * The following also reacquires the RPM reference the core passed
+ * to the driver during loading, which is dropped in
+ * intel_runtime_pm_enable(). We have to hand back the control of the
+ * device to the core with this reference held.
+ */
intel_display_set_init_power(dev_priv, true);
/* Remove the refcount we took to keep power well support disabled. */
@@ -2313,6 +2319,11 @@
pm_runtime_mark_last_busy(device);
pm_runtime_use_autosuspend(device);
+ /*
+ * The core calls the driver load handler with an RPM reference held.
+ * We drop that here and will reacquire it during unloading in
+ * intel_power_domains_fini().
+ */
pm_runtime_put_autosuspend(device);
}