wifi: ath12k: handle regulatory hints during mac registration

If a regulatory notification is there in the system while the hardware is
being registered, it attempts to set the new regulatory country. However,
ath12k currently boots with a default country derived from the BDF. If this
default country differs from the one provided in the notification, a race
condition can occur while updating the regulatory information back to
userspace. This potentially leads to driver having the incorrect regulatory
applied.

For example, suppose the regulatory domain for France (FR) is already
applied, and then the driver is loaded with a BDF that has the United
States (US) country programmed. When the driver finishes loading, the
regulatory domain shown in phyX still reflects the US regulatory settings.
This is incorrect, as the driver had already received a notification for
FR during hardware registration, but failed to process it properly due to
the race condition.

The race condition exists during driver initialization and hardware
registration:
- On driver load, the firmware sends BDF-based country regulatory rules,
  which are stored in default_regd via ath12k_reg_handle_chan_list().

- During hardware registration, a regulatory notification is triggered
  through:
    ath12k_mac_hw_register()
      -> ieee80211_register_hw()
        -> wiphy_register()
          -> wiphy_regulatory_register()
            -> reg_call_notifier()

  This sends a country code to the firmware, which responds with updated
  regulatory rules.

- After registration, ath12k_mac_hw_register() calls ath12k_regd_update(),
  which copies default_regd and passes it to the upper layers.

The race occurs between the firmware's response and the execution of
ath12k_regd_update(). If the firmware's new rules are processed before the
update call, the correct values are used. Otherwise, outdated boot-time
country settings are exposed to userspace.

To resolve this issue, introduce a completion mechanism within the hardware
group (ah). Trigger this completion whenever a regulatory change is
requested from the firmware. Then, in ath12k_regd_update(), wait for the
firmware to complete its regulatory processing before proceeding with the
update.

This ensures that during driver load, the default country is processed
first. However, before ath12k_regd_update() is called, the new regulatory
notification will have already been received by the driver. As a result, it
will wait for the firmware's regulatory processing to complete, and only
the final, correct regulatory domain will be updated to userspace.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.4.1-00199-QCAHKSWPL_SILICONZ-1

Signed-off-by: Aditya Kumar Singh <aditya.kumar.singh@oss.qualcomm.com>
Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Link: https://patch.msgid.link/20250617-handle_user_regd_update_hints_during_insmod-v2-1-10a6a48efe81@oss.qualcomm.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>

0 files changed, 0 insertions, 0 deletions