test0r
093a5038b8
The BES2600 firmware refuses WSM start-scan for 5 GHz with status 2
("rejected by policy"). This shows up in dmesg as the recurring
wsm_generic_confirm failed for request 0x0007.
[SCAN] Scan failed (-22).
pattern (besser issue #1, ~14-16/h on ohm/PineTab2 baseline).
Trace shows every reject is the second of a back-to-back pair: mac80211
splits multi-band hw_scan requests per band when the driver does not
set IEEE80211_HW_SINGLE_SCAN_ON_ALL_BANDS (we don't), then re-invokes
drv_hw_scan from __ieee80211_scan_completed for each subsequent band.
The 2.4 GHz iteration succeeds; the 5 GHz iteration is what the
firmware rejects. See ieee80211_prep_hw_scan in net/mac80211/scan.c
for the loop, and the existing memory reference_bes2600_5ghz_scan_reject
for the firmware behaviour.
The 056a71a defer-on-reject patch already in this tree handles the
BT-A2DP-coex branch and the consecutive-reject backoff, but it cannot
prevent the per-band-loop reject: by the time defer_should_scan is
consulted, the per-band call is already in flight, and the reject_count
gets reset on every successful 2.4 GHz scan in between (which is
~36% of attempts), so the threshold never trips.
The fix: refuse the 5 GHz iteration upfront in bes2600_hw_scan. The
2.4 GHz scan still runs normally. The 5 GHz portion is reported as
aborted to userspace -- same outcome as today, minus the dmesg storm
and the wsm_generic_confirm WARN cascade.
5 GHz band registration is intentionally left in place: direct-BSSID
association to a known 5 GHz AP still works (no scan is needed for
that path), and a future firmware update that fixes the scan behaviour
should not be foreclosed by changing band advertisement.
Contract: per include/net/mac80211.h ieee80211_ops.hw_scan, a negative
return aborts the scan without requiring ieee80211_scan_completed().
-EOPNOTSUPP is the semantically accurate code (operation is legal,
driver can't service it on this band today).
Phase 3 evidence:
- baseline N=3: rate ~14.3-23.6/h converged at 14.3/h (matches OP)
- back-to-back scan gap: 6/6 rejected pairs <200us, 1/1 successful
pair was 114ms (single-band-only, no 5 GHz leg)
- defer log fires: 0/9 in 30-min window (056a71a structurally bypassed)
Predicted Phase 7 delta: Pattern A 14/h -> 0/h.