[PATCH v3 2/2] ARM: dts: armada: WRT3200ACM: add marvell,ignore-regulatory-hint

[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 use of 5 GHz and DFS channels. This also affects phy0.

Add a device-tree flag marvell,ignore-regulatory-hint to the WRT3200ACM
device-tree, which signals mwifiex to ignore an incorrect regulatory hint
in the ROM, so userspace can set the correct platform regulatory domain.
The radios in WRT3200ACM/WRT32x are locked to the hard-coded configuration
for which they are certified, so the only impact is that the region
conflict is avoided and the 5 GHz radios can be used.

The Linux kernel sources do not have support for WRT32x. An equivalent
patch for these routers has to be sent to OpenWrt.

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

Tested-on: WRT3200ACM, OpenWrt
Cc: stable@vger.kernel.org
Signed-off-by: Georgi Valkov <gvalkov@gmail.com>
---
 arch/arm/boot/dts/marvell/armada-385-linksys-rango.dts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/boot/dts/marvell/armada-385-linksys-rango.dts b/arch/arm/boot/dts/marvell/armada-385-linksys-rango.dts
index 4ab45f294de2..6e283e223ca4 100644
--- a/arch/arm/boot/dts/marvell/armada-385-linksys-rango.dts
+++ b/arch/arm/boot/dts/marvell/armada-385-linksys-rango.dts
@@ -14,6 +14,7 @@ / {
 	model = "Linksys WRT3200ACM";
 	compatible = "linksys,rango", "linksys,armada385", "marvell,armada385",
 		     "marvell,armada380";
+	marvell,ignore-regulatory-hint;
 };
 
 &expander0 {
-- 
2.55.0