[PATCH ath-next 0/2] wifi: ath11k: fix SoC reboot on firmware crash on AHB

[Julius Bairaktaris]

On IPQ8074 every firmware assert takes the whole SoC down. The DP NAPI
keeps polling while ath11k_core_reconfigure_on_crash() frees the data
path underneath it, and dereferences a ring the teardown has already
cleared.

The interrupts used to be disabled at the top of that function.
commit d455e805de70 ("wifi: ath11k: rearrange IRQ enable/disable in reset path")
moved the disable into ath11k_core_reset(), which AHB parts never reach
on a real firmware crash: reset_work is queued only from mhi.c and from
the debugfs hw-restart handler. Patch 2 puts the disable back on the
crash path. Patch 1 is a prerequisite - the CE half of the quiesce is a
no-op on AHB today because the bus never implemented the hif ops.

Reproduced and fixed on a Xiaomi AX3600 (IPQ8074 hw2.0), with no
out-of-tree modules loaded, using the debugfs simulate_fw_crash
'assert' trigger:

  before: 2/2 asserts panic in ath11k_dp_rx_process_mon_status() and
          reboot the SoC
  after:  3/3 asserts recover, 5 firmware boots across a single 397 s
          uptime, no panics, both radios stay up

Note the debugfs 'hw-restart' trigger does not reproduce this, since it
goes through ath11k_core_reset() - the one path that still disables the
interrupts. Only a real firmware assert does.

Patch 1 is by inspection: it makes ath11k_hif_ce_irq_disable() take
effect on AHB, which also fixes the existing call in
ath11k_core_reset(). I have not managed to trigger a CE-side crash on
its own, so if you would rather see that split out or dropped, say so.

Julius Bairaktaris (2):
  wifi: ath11k: implement CE interrupt enable/disable for AHB
  wifi: ath11k: disable interrupts during firmware crash recovery

 drivers/net/wireless/ath/ath11k/ahb.c  | 9 ++++++++-
 drivers/net/wireless/ath/ath11k/core.c | 9 +++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

-- 
2.53.0