Does MT76 read RF data from "flash" or "efuse" for MT7602E/MT7612E?

bahtsiz_bedevi · January 6, 2023, 8:25pm

I have wireless issues with MT76 driver for a long time.
Wifi is becoming unstable and extremely slow occasionally. Even file transfers fail due to network errors.
I contacted the vendor and they gave me this.

Does MT76 read RF data from "flash" or "efuse" for MT7602E/MT7612E?
board: unielec_u7621-06-16m

root@OpenWrt:~# cat /etc/os-release
NAME="OpenWrt"
VERSION="SNAPSHOT"
ID="openwrt"
ID_LIKE="lede openwrt"
PRETTY_NAME="OpenWrt SNAPSHOT"
VERSION_ID="snapshot"
HOME_URL="https://openwrt.org/"
BUG_URL="https://bugs.openwrt.org/"
SUPPORT_URL="https://forum.openwrt.org/"
BUILD_ID="r21549-963c77158c"
OPENWRT_BOARD="ramips/mt7621"
OPENWRT_ARCH="mipsel_24kc"
OPENWRT_TAINTS=""
OPENWRT_DEVICE_MANUFACTURER="OpenWrt"
OPENWRT_DEVICE_MANUFACTURER_URL="https://openwrt.org/"
OPENWRT_DEVICE_PRODUCT="Generic"
OPENWRT_DEVICE_REVISION="v0"
OPENWRT_RELEASE="OpenWrt SNAPSHOT r21549-963c77158c"

mPCIe cards info is here blow.

root@OpenWrt:~# lspci
00:00.0 PCI bridge: Device 0e8d:0801 (rev 01)
00:01.0 PCI bridge: Device 0e8d:0801 (rev 01)
00:02.0 PCI bridge: Device 0e8d:0801 (rev 01)
01:00.0 SATA controller: ASMedia Technology Inc. ASM1062 Serial ATA Controller (rev 01)
02:00.0 Network controller: MEDIATEK Corp. MT7612E 802.11acbgn PCI Express Wireless Network Adapter
03:00.0 Network controller: MEDIATEK Corp. Device 7602

I've created several bug reports on mt76 github but that place seems like a quiet place.

daniel · January 8, 2023, 8:20pm

Sorry, but this is wrong. The mt76 driver used by OpenWrt does allow to read RF calibration data (and not just the MAC addresses) from flash and this is how it is done on the vast majority of embedded devices. Currently the location of the RF calibration data is defined using a custom device tree property, see for example

github.com

openwrt/openwrt/blob/master/target/linux/ramips/dts/mt7621_youku_yk-l2.dts#L127


      
          		led {
          			led-active-low;
          		};
          	};
          };
          
          
&pcie1 {
          	wifi@0,0 {
          		compatible = "pci14c3,7662";
          		reg = <0x0000 0 0 0 0>;
          		mediatek,mtd-eeprom = <&factory 0x8000>;
          		ieee80211-freq-limit = <5000000 6000000>;
          		led {
          			led-sources = <2>;
          			led-active-low;
          		};
          	};
          };
          
          
&gmac0 {
          	nvmem-cells = <&macaddr_factory_e000>;

bahtsiz_bedevi · January 8, 2023, 9:55pm

MT7621 routers with built-in wireless chips have this setting in their DTS files.
But my router unielec_u7621-06-16m is different. mPCIe wireless cards are purchased separately.

Manufacturer says RF data must be read from EFUSE, not from factory flash.
I couldn't find the same lines in the router's dts file:

github.com

openwrt/openwrt/blob/master/target/linux/ramips/dts/mt7621_unielec_u7621-06-16m.dts

// SPDX-License-Identifier: BSD-3-Clause
/*
 *  Copyright(c) 2017 Kristian Evensen <kristian.evensen@gmail.com>.
 *  Copyright(c) 2017 Piotr Dymacz <pepe2k@gmail.com>.
 *  All rights reserved.
 */

#include "mt7621_unielec_u7621-06.dtsi"

/ {
	compatible = "unielec,u7621-06-16m", "unielec,u7621-06", "mediatek,mt7621-soc";
	model = "UniElec U7621-06 (16M flash)";
};

&spi0 {
	status = "okay";

	flash@0 {
		compatible = "jedec,spi-nor";
		reg = <0>;

This file has been truncated. show original

daniel · January 8, 2023, 10:30pm

If calibration data is stored in the efuse of the module's chip, then you don't need to do anything. The driver will load it from there (for example for mt76x2 which often go together with U7621-06 board):

github.com

openwrt/mt76/blob/master/mt76x2/eeprom.c#L163


      
          		found = !mt76x2_check_eeprom(dev);
          
          
	dev->mt76.otp.data = devm_kzalloc(dev->mt76.dev, MT7662_EEPROM_SIZE,
          					  GFP_KERNEL);
          	dev->mt76.otp.size = MT7662_EEPROM_SIZE;
          	if (!dev->mt76.otp.data)
          		return -ENOMEM;
          
          
	efuse = dev->mt76.otp.data;
          
          
	if (mt76x02_get_efuse_data(dev, 0, efuse, MT7662_EEPROM_SIZE,
          				   MT_EE_READ))
          		goto out;
          
          
	if (found) {
          		mt76x2_apply_cal_free_data(dev, efuse);
          	} else {
          		/* FIXME: check if efuse data is complete */
          		found = true;
          		memcpy(dev->mt76.eeprom.data, efuse, MT7662_EEPROM_SIZE);
          	}

bahtsiz_bedevi · January 8, 2023, 10:36pm

Thanks for the confirmation

system · January 18, 2023, 10:36pm

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