Merge tag 'cpuidle_psci-v5.5-rc4' of git://git.linaro.org/people/ulf.hansson/linux-pm into arm/drivers

Initial support for hierarchical CPU arrangement, managed by PSCI and its
corresponding cpuidle driver. This support is based upon using the generic
PM domain, which already supports devices belonging to CPUs.

Finally, these is a DTS patch that enables the hierarchical topology to be
used for the Qcom 410c Dragonboard, which supports the PSCI OS-initiated
mode.

* tag 'cpuidle_psci-v5.5-rc4' of git://git.linaro.org/people/ulf.hansson/linux-pm: (611 commits)
  arm64: dts: Convert to the hierarchical CPU topology layout for MSM8916
  cpuidle: psci: Add support for PM domains by using genpd
  PM / Domains: Introduce a genpd OF helper that removes a subdomain
  cpuidle: psci: Support CPU hotplug for the hierarchical model
  cpuidle: psci: Manage runtime PM in the idle path
  cpuidle: psci: Prepare to use OS initiated suspend mode via PM domains
  cpuidle: psci: Attach CPU devices to their PM domains
  cpuidle: psci: Add a helper to attach a CPU to its PM domain
  cpuidle: psci: Support hierarchical CPU idle states
  cpuidle: psci: Simplify OF parsing of CPU idle state nodes
  cpuidle: dt: Support hierarchical CPU idle states
  of: base: Add of_get_cpu_state_node() to get idle states for a CPU node
  firmware: psci: Export functions to manage the OSI mode
  dt: psci: Update DT bindings to support hierarchical PSCI states
  cpuidle: psci: Align psci_power_state count with idle state count
  Linux 5.5-rc4
  locks: print unsigned ino in /proc/locks
  riscv: export flush_icache_all to modules
  riscv: reject invalid syscalls below -1
  riscv: fix compile failure with EXPORT_SYMBOL() & !MMU
  ...

Link: https://lore.kernel.org/r/20200102160820.3572-1-ulf.hansson@linaro.org
Signed-off-by: Olof Johansson <olof@lixom.net>

1 files changed, 31 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_frontbuffer.h b/drivers/gpu/drm/i915/display/intel_frontbuffer.h
index adc64d61a4a5..6d41f5394425 100644
--- a/drivers/gpu/drm/i915/display/intel_frontbuffer.h
+++ b/drivers/gpu/drm/i915/display/intel_frontbuffer.h
@@ -27,10 +27,10 @@
 #include <linux/atomic.h>
 #include <linux/kref.h>
 
+#include "gem/i915_gem_object_types.h"
 #include "i915_active.h"
 
 struct drm_i915_private;
-struct drm_i915_gem_object;
 
 enum fb_op_origin {
 	ORIGIN_GTT,
@@ -45,6 +45,7 @@ struct intel_frontbuffer {
 	atomic_t bits;
 	struct i915_active write;
 	struct drm_i915_gem_object *obj;
+	struct rcu_head rcu;
 };
 
 void intel_frontbuffer_flip_prepare(struct drm_i915_private *i915,
@@ -54,6 +55,35 @@ void intel_frontbuffer_flip_complete(struct drm_i915_private *i915,
 void intel_frontbuffer_flip(struct drm_i915_private *i915,
 			    unsigned frontbuffer_bits);
 
+void intel_frontbuffer_put(struct intel_frontbuffer *front);
+
+static inline struct intel_frontbuffer *
+__intel_frontbuffer_get(const struct drm_i915_gem_object *obj)
+{
+	struct intel_frontbuffer *front;
+
+	if (likely(!rcu_access_pointer(obj->frontbuffer)))
+		return NULL;
+
+	rcu_read_lock();
+	do {
+		front = rcu_dereference(obj->frontbuffer);
+		if (!front)
+			break;
+
+		if (unlikely(!kref_get_unless_zero(&front->ref)))
+			continue;
+
+		if (likely(front == rcu_access_pointer(obj->frontbuffer)))
+			break;
+
+		intel_frontbuffer_put(front);
+	} while (1);
+	rcu_read_unlock();
+
+	return front;
+}
+
 struct intel_frontbuffer *
 intel_frontbuffer_get(struct drm_i915_gem_object *obj);
 
@@ -119,6 +149,4 @@ void intel_frontbuffer_track(struct intel_frontbuffer *old,
 			     struct intel_frontbuffer *new,
 			     unsigned int frontbuffer_bits);
 
-void intel_frontbuffer_put(struct intel_frontbuffer *front);
-
 #endif /* __INTEL_FRONTBUFFER_H__ */