Commit 05646543 authored by Chris Wilson's avatar Chris Wilson

drm/i915: Acquire uncore.lock over intel_uncore_wait_for_register()

We acquire the forcewake and use I915_READ_FW instead for the atomic
wait within intel_uncore_wait_for_register. However, this still leaves
us vulnerable to concurrent mmio access to the register, which can cause
system hangs on gen7. The protection is to acquire uncore.lock around
each register, so lets add it back.

v2: Wrap __intel_wait_for_register_fw() to re-use its atomic wait_for
loop and spare adding another for ourselves.
v3: Add might_sleep() annotation
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170411101340.31994-3-chris@chris-wilson.co.ukReviewed-by: default avatarTvrtko Ursulin <tvrtko.ursulin@intel.com>
parent 02b312d0
...@@ -1662,14 +1662,22 @@ int intel_wait_for_register(struct drm_i915_private *dev_priv, ...@@ -1662,14 +1662,22 @@ int intel_wait_for_register(struct drm_i915_private *dev_priv,
u32 value, u32 value,
unsigned int timeout_ms) unsigned int timeout_ms)
{ {
unsigned fw = unsigned fw =
intel_uncore_forcewake_for_reg(dev_priv, reg, FW_REG_READ); intel_uncore_forcewake_for_reg(dev_priv, reg, FW_REG_READ);
int ret; int ret;
intel_uncore_forcewake_get(dev_priv, fw); might_sleep();
ret = wait_for_us((I915_READ_FW(reg) & mask) == value, 2);
intel_uncore_forcewake_put(dev_priv, fw); spin_lock_irq(&dev_priv->uncore.lock);
intel_uncore_forcewake_get__locked(dev_priv, fw);
ret = __intel_wait_for_register_fw(dev_priv,
reg, mask, value,
2, 0, NULL);
intel_uncore_forcewake_put__locked(dev_priv, fw);
spin_unlock_irq(&dev_priv->uncore.lock);
if (ret) if (ret)
ret = wait_for((I915_READ_NOTRACE(reg) & mask) == value, ret = wait_for((I915_READ_NOTRACE(reg) & mask) == value,
timeout_ms); timeout_ms);
......
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