From d7a133d886b45651e36e7065998b1413d379ac1f Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Thu, 7 Sep 2017 14:44:41 +0100 Subject: drm/i915: Disable mmio debugging during user access If the user bypasses i915 and accesses mmio directly, that easily confuses our automatic mmio debugging (any error we then detect is likely to be as a result of the user). Since we expect userspace to open debugfs/i915_forcewake_user if i915.ko is loaded and they want mmio access, that makes the opportune time to disable our debugging for duration of the bypass. v2: Move the fiddling of uncore internals to uncore.c References: https://bugs.freedesktop.org/show_bug.cgi?id=102543 Signed-off-by: Chris Wilson Cc: Mika Kuoppala Reviewed-by: Mika Kuoppala Link: https://patchwork.freedesktop.org/patch/msgid/20170907134441.12881-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/intel_uncore.c | 51 +++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) (limited to 'drivers/gpu/drm/i915/intel_uncore.c') diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c index 0529af7cfbb8..1b38eb94d461 100644 --- a/drivers/gpu/drm/i915/intel_uncore.c +++ b/drivers/gpu/drm/i915/intel_uncore.c @@ -489,6 +489,57 @@ void intel_uncore_forcewake_get(struct drm_i915_private *dev_priv, spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags); } +/** + * intel_uncore_forcewake_user_get - claim forcewake on behalf of userspace + * @dev_priv: i915 device instance + * + * This function is a wrapper around intel_uncore_forcewake_get() to acquire + * the GT powerwell and in the process disable our debugging for the + * duration of userspace's bypass. + */ +void intel_uncore_forcewake_user_get(struct drm_i915_private *dev_priv) +{ + spin_lock_irq(&dev_priv->uncore.lock); + if (!dev_priv->uncore.user_forcewake.count++) { + intel_uncore_forcewake_get__locked(dev_priv, FORCEWAKE_ALL); + + /* Save and disable mmio debugging for the user bypass */ + dev_priv->uncore.user_forcewake.saved_mmio_check = + dev_priv->uncore.unclaimed_mmio_check; + dev_priv->uncore.user_forcewake.saved_mmio_debug = + i915.mmio_debug; + + dev_priv->uncore.unclaimed_mmio_check = 0; + i915.mmio_debug = 0; + } + spin_unlock_irq(&dev_priv->uncore.lock); +} + +/** + * intel_uncore_forcewake_user_put - release forcewake on behalf of userspace + * @dev_priv: i915 device instance + * + * This function complements intel_uncore_forcewake_user_get() and releases + * the GT powerwell taken on behalf of the userspace bypass. + */ +void intel_uncore_forcewake_user_put(struct drm_i915_private *dev_priv) +{ + spin_lock_irq(&dev_priv->uncore.lock); + if (!--dev_priv->uncore.user_forcewake.count) { + if (intel_uncore_unclaimed_mmio(dev_priv)) + dev_info(dev_priv->drm.dev, + "Invalid mmio detected during user access\n"); + + dev_priv->uncore.unclaimed_mmio_check = + dev_priv->uncore.user_forcewake.saved_mmio_check; + i915.mmio_debug = + dev_priv->uncore.user_forcewake.saved_mmio_debug; + + intel_uncore_forcewake_put__locked(dev_priv, FORCEWAKE_ALL); + } + spin_unlock_irq(&dev_priv->uncore.lock); +} + /** * intel_uncore_forcewake_get__locked - grab forcewake domain references * @dev_priv: i915 device instance -- cgit v1.2.3-59-g8ed1b