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Commit 2b19efeb authored by Imre Deak's avatar Imre Deak
Browse files

drm/i915: add support for checking RPM atomic sections 



In some cases we want to check whether we hold an RPM wakelock reference
for the whole duration of a sequence. To achieve this add a new RPM
atomic sequence counter that we increment any time the wakelock refcount
drops to zero.  Check whether the sequence number stays the same during
the atomic section and that we hold the wakelock at the beginning of the
section.

Motivated by Chris.

v2-v3:
- unchanged
v4:
- swap the order of atomic_read() and assert_rpm_wakelock_held() in
  assert_rpm_atomic_begin() to avoid race

Signed-off-by: default avatarImre Deak <imre.deak@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> (v3)
Reviewed-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1450203038-5150-10-git-send-email-imre.deak@intel.com
parent 542db3cd

drivers/gpu/drm/i915/i915_drv.h

+1 −0
Original line number Diff line number Diff line
@@ -1606,6 +1606,7 @@ struct skl_wm_level { 
 */

struct i915_runtime_pm {

	atomic_t wakeref_count;

	atomic_t atomic_seq;

	bool suspended;

	bool irqs_enabled;

};

drivers/gpu/drm/i915/intel_drv.h

+17 −0
Original line number Diff line number Diff line
@@ -1446,6 +1446,23 @@ assert_rpm_wakelock_held(struct drm_i915_private *dev_priv) 
		  "RPM wakelock ref not held during HW access");

}



static inline int

assert_rpm_atomic_begin(struct drm_i915_private *dev_priv)

{

	int seq = atomic_read(&dev_priv->pm.atomic_seq);



	assert_rpm_wakelock_held(dev_priv);



	return seq;

}



static inline void

assert_rpm_atomic_end(struct drm_i915_private *dev_priv, int begin_seq)

{

	WARN_ONCE(atomic_read(&dev_priv->pm.atomic_seq) != begin_seq,

		  "HW access outside of RPM atomic section\n");

}



/**

 * disable_rpm_wakeref_asserts - disable the RPM assert checks

 * @dev_priv: i915 device instance

drivers/gpu/drm/i915/intel_pm.c

+1 −0
Original line number Diff line number Diff line
@@ -7247,4 +7247,5 @@ void intel_pm_setup(struct drm_device *dev) 


	dev_priv->pm.suspended = false;

	atomic_set(&dev_priv->pm.wakeref_count, 0);

	atomic_set(&dev_priv->pm.atomic_seq, 0);

}

drivers/gpu/drm/i915/intel_runtime_pm.c

+2 −1
Original line number Diff line number Diff line
@@ -2287,7 +2287,8 @@ void intel_runtime_pm_put(struct drm_i915_private *dev_priv) 
	struct device *device = &dev->pdev->dev;



	assert_rpm_wakelock_held(dev_priv);

	atomic_dec(&dev_priv->pm.wakeref_count);

	if (atomic_dec_and_test(&dev_priv->pm.wakeref_count))

		atomic_inc(&dev_priv->pm.atomic_seq);



	pm_runtime_mark_last_busy(device);

	pm_runtime_put_autosuspend(device);