[PATCH v6 2/3] wifi: mwifiex: add dt flag to avoid conflict with platform reg domain

[Georgi Valkov <gvalkov@gmail.com>]

WRT3200ACM and WRT32x routers always report a fixed US regulatory domain
from the mwifiex ROM, which conflicts with the platform regulatory
configuration on units sold outside the US market. For example:
- phy0 mwlwifi 5 GHz, hard-coded region 98 EU mapped to FR
- phy1 mwlwifi 2.4 GHz, hard-coded region 98 EU mapped to FR
- phy2 mwifiex 2.4 and 5 GHz, hard-coded region US

When the system boots, it detects a conflict between the user selected
region and the radios, e.g. BG FR US, and applies extreme restrictions,
preventing phy0 from starting on any DFS channel. phy2 works.

Add a device-tree flag, which allows affected devices, where the radio
conflicts with the platform to ignore the incorrect regulatory hint in
the ROM of the radio, so the platform regulatory domain can be used.
This does not allow the user to change the regulatory configuration of
any radio. It only allows phy0 to start and operate according to its
certified configuration.

The change affects only platforms which explicitly define this flag, and
helps overcome the incorrect behaviour of proprietary radio firmware.

[1] https://github.com/kaloz/mwlwifi/issues/173#issuecomment-307879699
[2] https://github.com/openwrt/openwrt/issues/9956

Tested-on WRT3200ACM, OpenWrt
iw reg get: no longer reports region for phy2

Cc: stable@vger.kernel.org
Signed-off-by: Georgi Valkov <gvalkov@gmail.com>
---
 drivers/net/wireless/marvell/mwifiex/cfg80211.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/net/wireless/marvell/mwifiex/cfg80211.c b/drivers/net/wireless/marvell/mwifiex/cfg80211.c
index 7a1ba32f1fb3..293876397b67 100644
--- a/drivers/net/wireless/marvell/mwifiex/cfg80211.c
+++ b/drivers/net/wireless/marvell/mwifiex/cfg80211.c
@@ -4897,7 +4897,14 @@ int mwifiex_register_cfg80211(struct mwifiex_adapter *adapter)
 				country_code =
 					mwifiex_11d_code_2_region(
 						adapter->region_code);
+
+				/* If the reg hint in ROM conflicts with platform
+				 * configuration, it should be ignored, so the
+				 * platform regulatory domain can be used.
+				 */
 				if (country_code &&
+				    !device_property_read_bool(adapter->dev,
+							       "marvell,invalid-reg-hint-in-rom") &&
 				    regulatory_hint(wiphy, country_code))
 					mwifiex_dbg(priv->adapter, ERROR,
 						    "regulatory_hint() failed\n");
-- 
2.55.0