From 2b19efebf175bb2120c5ae00b8e79febe73d225a Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Tue, 15 Dec 2015 20:10:37 +0200 Subject: [PATCH] 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: Imre Deak Reviewed-by: Chris Wilson (v3) Reviewed-by: Joonas Lahtinen Link: http://patchwork.freedesktop.org/patch/msgid/1450203038-5150-10-git-send-email-imre.deak@intel.com --- drivers/gpu/drm/i915/i915_drv.h | 1 + drivers/gpu/drm/i915/intel_drv.h | 17 +++++++++++++++++ drivers/gpu/drm/i915/intel_pm.c | 1 + drivers/gpu/drm/i915/intel_runtime_pm.c | 3 ++- 4 files changed, 21 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 74f1d78cbe2e..1943b8f0e684 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -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; }; diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index eff7d2e7d71b..d523ebb2f89d 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -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 diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 3232305301ca..8d0d6f59a72b 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -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); } diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c index 4c80d2adac70..a0b9eaf77fe9 100644 --- a/drivers/gpu/drm/i915/intel_runtime_pm.c +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c @@ -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); -- 2.20.1