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drm/i915: Don't allow overuse of __intel_wait_for_register_fw()

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This function should not be called with long timeouts in atomic context.
Annotate it as might_sleep if timeout is longer than 10us.

v2: fix comment (Michal)

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170410121747.209200-1-michal.wajdeczko@intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
This commit is contained in:
Michal Wajdeczko 2017-04-10 12:17:47 +00:00 committed by Chris Wilson
parent 3fc7d86b32
commit 6976e74b5f
1 changed files with 5 additions and 0 deletions
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5
drivers/gpu/drm/i915/intel_uncore.c
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@ -1600,6 +1600,8 @@ static int gen6_reset_engines(struct drm_i915_private *dev_priv,
* (I915_READ_FW(reg) & mask) == value
*
* Otherwise, the wait will timeout after @slow_timeout_ms milliseconds.
* For atomic context @slow_timeout_ms must be zero and @fast_timeout_us
* must be not larger than 10 microseconds.
*
* Note that this routine assumes the caller holds forcewake asserted, it is
* not suitable for very long waits. See intel_wait_for_register() if you
@ -1620,6 +1622,9 @@ int __intel_wait_for_register_fw(struct drm_i915_private *dev_priv,
#define done (((reg_value = I915_READ_FW(reg)) & mask) == value)
int ret;
/* Catch any overuse of this function */
might_sleep_if(fast_timeout_us > 10 || slow_timeout_ms);
if (fast_timeout_us > 10)
ret = _wait_for(done, fast_timeout_us, 10);
else