drm/i915/execlists: Relax the locked clear_bit(IRQ_EXECLIST)

We only need to care about the ordering of the clearing of the bit with
the uncached CSB read in order to correctly detect a new interrupt
before the read completes. The uncached read itself acts as a full
memory barrier, so we do not need to enforce another in the form of a
locked clear_bit.

v2: Clarify why the split and unlocked test/clear is harmless.

Signed-off-by: Chris Wilson <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]
Reviewed-by: Tvrtko Ursulin <[email protected]>

0 files changed, 0 insertions, 0 deletions