forked from Minki/linux
523e7c9278
During a reset, we may skip over completed requests and lost context-switch interrupts. Following the reset, we may then may end up with no active requests in the ELSP (and so do not resubmit to restart the engine), but have a queue of requests ready for execution. This is unlikely, it requires the last request to complete after the hang is detected, but not impossible. The outcome of this is that the engine stalls, possibly leading to full ring and indefinite wait under struct_mutex, eventually leading to a full driver hang. Alternatively, we can solve this by unsubmitting the incomplete requests and just kickstarting the tasklet. Michał has patches for that, which I initially disliked due to the extra complexity, but the complexity of this "simple" restart is growing... Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Michał Winiarski <michal.winiarski@intel.com> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20170916204414.32762-1-chris@chris-wilson.co.uk Reviewed-by: Michał Winiarski <michal.winiarski@intel.com> |
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