From: Imre Deak Date: Wed, 17 Feb 2016 12:17:42 +0000 (+0200) Subject: drm/i915: Add helper to get a display power ref if it was already enabled X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=09731280028ce03e6a27e1998137f1775a2839f3;p=linux-beck.git drm/i915: Add helper to get a display power ref if it was already enabled We have many places in the code where we check if a given display power domain is enabled and if so access registers backed by this power domain. We assumed that some modeset lock will prevent the power reference from vanishing in the middle of the HW access, but this assumption doesn't always hold. In such cases we get either the wakeref not held, or an unclaimed register access error message. To fix this in a future-proof way that's independent of other locks wrap any such access with a get_ref_if_enabled()/put_ref() pair. Kudos to Ville and Joonas for the ideas of this new interface. v2: - init the power_domains ptr when declaring it everywhere (Joonas) v3: - don't report the device to be powered if runtime PM is disabled CC: Mika Kuoppala CC: Chris Wilson CC: Joonas Lahtinen CC: Ville Syrjälä Signed-off-by: Imre Deak Reviewed-by: Joonas Lahtinen Link: http://patchwork.freedesktop.org/patch/msgid/1455711462-7442-1-git-send-email-imre.deak@intel.com --- diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index 3cae3768ea37..f95f8b22939f 100644 --- a/drivers/gpu/drm/i915/intel_drv.h +++ b/drivers/gpu/drm/i915/intel_drv.h @@ -1436,6 +1436,8 @@ bool __intel_display_power_is_enabled(struct drm_i915_private *dev_priv, enum intel_display_power_domain domain); void intel_display_power_get(struct drm_i915_private *dev_priv, enum intel_display_power_domain domain); +bool intel_display_power_get_if_enabled(struct drm_i915_private *dev_priv, + enum intel_display_power_domain domain); void intel_display_power_put(struct drm_i915_private *dev_priv, enum intel_display_power_domain domain); @@ -1522,6 +1524,7 @@ enable_rpm_wakeref_asserts(struct drm_i915_private *dev_priv) enable_rpm_wakeref_asserts(dev_priv) void intel_runtime_pm_get(struct drm_i915_private *dev_priv); +bool intel_runtime_pm_get_if_in_use(struct drm_i915_private *dev_priv); void intel_runtime_pm_get_noresume(struct drm_i915_private *dev_priv); void intel_runtime_pm_put(struct drm_i915_private *dev_priv); diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c index bbca527184d0..a2e367cf99a2 100644 --- a/drivers/gpu/drm/i915/intel_runtime_pm.c +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c @@ -1435,6 +1435,22 @@ static void chv_pipe_power_well_disable(struct drm_i915_private *dev_priv, chv_set_pipe_power_well(dev_priv, power_well, false); } +static void +__intel_display_power_get_domain(struct drm_i915_private *dev_priv, + enum intel_display_power_domain domain) +{ + struct i915_power_domains *power_domains = &dev_priv->power_domains; + struct i915_power_well *power_well; + int i; + + for_each_power_well(i, power_well, BIT(domain), power_domains) { + if (!power_well->count++) + intel_power_well_enable(dev_priv, power_well); + } + + power_domains->domain_use_count[domain]++; +} + /** * intel_display_power_get - grab a power domain reference * @dev_priv: i915 device instance @@ -1450,24 +1466,53 @@ static void chv_pipe_power_well_disable(struct drm_i915_private *dev_priv, void intel_display_power_get(struct drm_i915_private *dev_priv, enum intel_display_power_domain domain) { - struct i915_power_domains *power_domains; - struct i915_power_well *power_well; - int i; + struct i915_power_domains *power_domains = &dev_priv->power_domains; intel_runtime_pm_get(dev_priv); - power_domains = &dev_priv->power_domains; + mutex_lock(&power_domains->lock); + + __intel_display_power_get_domain(dev_priv, domain); + + mutex_unlock(&power_domains->lock); +} + +/** + * intel_display_power_get_if_enabled - grab a reference for an enabled display power domain + * @dev_priv: i915 device instance + * @domain: power domain to reference + * + * This function grabs a power domain reference for @domain and ensures that the + * power domain and all its parents are powered up. Therefore users should only + * grab a reference to the innermost power domain they need. + * + * Any power domain reference obtained by this function must have a symmetric + * call to intel_display_power_put() to release the reference again. + */ +bool intel_display_power_get_if_enabled(struct drm_i915_private *dev_priv, + enum intel_display_power_domain domain) +{ + struct i915_power_domains *power_domains = &dev_priv->power_domains; + bool is_enabled; + + if (!intel_runtime_pm_get_if_in_use(dev_priv)) + return false; mutex_lock(&power_domains->lock); - for_each_power_well(i, power_well, BIT(domain), power_domains) { - if (!power_well->count++) - intel_power_well_enable(dev_priv, power_well); + if (__intel_display_power_is_enabled(dev_priv, domain)) { + __intel_display_power_get_domain(dev_priv, domain); + is_enabled = true; + } else { + is_enabled = false; } - power_domains->domain_use_count[domain]++; - mutex_unlock(&power_domains->lock); + + if (!is_enabled) + intel_runtime_pm_put(dev_priv); + + return is_enabled; } /** @@ -2238,6 +2283,43 @@ void intel_runtime_pm_get(struct drm_i915_private *dev_priv) assert_rpm_wakelock_held(dev_priv); } +/** + * intel_runtime_pm_get_if_in_use - grab a runtime pm reference if device in use + * @dev_priv: i915 device instance + * + * This function grabs a device-level runtime pm reference if the device is + * already in use and ensures that it is powered up. + * + * Any runtime pm reference obtained by this function must have a symmetric + * call to intel_runtime_pm_put() to release the reference again. + */ +bool intel_runtime_pm_get_if_in_use(struct drm_i915_private *dev_priv) +{ + struct drm_device *dev = dev_priv->dev; + struct device *device = &dev->pdev->dev; + int ret; + + if (!IS_ENABLED(CONFIG_PM)) + return true; + + ret = pm_runtime_get_if_in_use(device); + + /* + * In cases runtime PM is disabled by the RPM core and we get an + * -EINVAL return value we are not supposed to call this function, + * since the power state is undefined. This applies atm to the + * late/early system suspend/resume handlers. + */ + WARN_ON_ONCE(ret < 0); + if (ret <= 0) + return false; + + atomic_inc(&dev_priv->pm.wakeref_count); + assert_rpm_wakelock_held(dev_priv); + + return true; +} + /** * intel_runtime_pm_get_noresume - grab a runtime pm reference * @dev_priv: i915 device instance