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gpu: host1x: Skip redundant HW state update

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When the fence list is empty, host1x_intr_update_hw_state()
falls through to host1x_intr_disable_syncpt_intr()
which does two MMIO writes to disable the syncpoint
interrupt and clear its status.

The ISR has already disabled and acked the interrupt
before calling host1x_intr_handle_interrupt(), making
these two writes redundant. Skip the update_hw_state()
call if no fences remain.

Measured Syncpoint wait latency (50000 samples):
  Average latency:   10.6 us  -> 9.4 us
  99.99 pct latency: 51.90 us -> 36.58 us

Signed-off-by: Tanmay Patil <tanmayp@nvidia.com>
Acked-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patch.msgid.link/20260514103153.766343-3-tanmayp@nvidia.com
This commit is contained in:
Tanmay Patil 2026-05-14 10:31:53 +00:00 committed by Thierry Reding
parent 6fea41ff36
commit 132926b217
1 changed files with 6 additions and 2 deletions
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8
drivers/gpu/host1x/intr.c
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@ -92,8 +92,12 @@ void host1x_intr_handle_interrupt(struct host1x *host, unsigned int id)
host1x_fence_signal(fence);
}
/* Re-enable interrupt if necessary */
host1x_intr_update_hw_state(host, sp);
/*
* Re-enable interrupt if necessary. The ISR already disabled the interrupt,
* so if no fences remain, no update is needed.
*/
if (!list_empty(&sp->fences.list))
host1x_intr_update_hw_state(host, sp);
spin_unlock(&sp->fences.lock);
}