ath10k load fails with `swiotlb buffer is full (sz: 1172264 bytes)`

[ojab //]

Oh hai!

I've changed motherboard and after that ath10k load fails with

[    5.677180] ath10k_pci 0000:03:00.0: swiotlb buffer is full (sz:
1172264 bytes)
[    5.677471] ath10k_pci 0000:03:00.0: swiotlb: coherent allocation
failed, size=1172264
[    5.677745] CPU: 4 PID: 137 Comm: kworker/u16:6 Not tainted 4.16.4-ojab #19
[    5.677964] Workqueue: ath10k_aux_wq
ath10k_wmi_event_service_ready_work [ath10k_core]
[    5.678238] Call Trace:
[    5.678403]  dump_stack+0x67/0x93
[    5.678575]  swiotlb_alloc_coherent+0x1da/0x1f0
[    5.678763]  ath10k_wmi_event_service_ready_work+0x3b0/0x670 [ath10k_core]
[    5.678978]  process_one_work+0x1d3/0x3c0
[    5.679158]  worker_thread+0x2e/0x400
[    5.679333]  ? trace_event_raw_event_workqueue_execute_start+0x100/0x100
[    5.679544]  kthread+0x113/0x130
[    5.679713]  ? kthread_create_worker+0x80/0x80
[    5.679897]  ret_from_fork+0x27/0x50

vanilla kernel 4.16.4, cards are WLE1216V5-23 & WLE1216V2-20 (both
QCA9884-based, fails with the same symptoms), motherboard is asus
A320M-K with iommu disabled.

How can I get it working?

//wbr ojab