From: Henk Vergonet henk.vergonet@gmail.com
[ Upstream commit 3c0e4f606d8693795a2c965d6f4987b1bfc31097 ]
Adds support for: - LiteOn WN4516R - LiteOn WN4519R Both use: - A nonstandard USB connector - Mediatek chipset MT7600U - ASIC revision: 76320044
Disabled VHT support on ASIC revision 76320044:
This fixes the 5G connectibity issue on LiteOn WN4519R module see https://github.com/openwrt/mt76/issues/971
And may also fix the 5G issues on the XBox One Wireless Adapter see https://github.com/openwrt/mt76/issues/200
I have looked at the FCC info related to the MT7632U chip as mentioned in here: https://github.com/openwrt/mt76/issues/459 These confirm the chipset does not support 'ac' mode and hence VHT should be turned of.
Signed-off-by: Henk Vergonet henk.vergonet@gmail.com Acked-by: Lorenzo Bianconi lorenzo@kernel.org Link: https://patch.msgid.link/20250418143914.31384-1-henk.vergonet@gmail.com Signed-off-by: Felix Fietkau nbd@nbd.name Signed-off-by: Sasha Levin sashal@kernel.org ---
**YES** This commit should be backported to stable kernel trees. Here's my detailed analysis: ## Comparison with Similar Commits This commit closely matches **Similar Commit #1** (XBox One wifi adapter support) which was marked as **YES** for backporting. Both commits: - Add new USB device IDs for wireless adapters - Include hardware-specific workarounds for device limitations - Fix connectivity issues for specific hardware ## Code Changes Analysis ### 1. USB Device ID Additions (Low Risk) ```c { USB_DEVICE(0x0471, 0x2126) }, /bin /bin.usr-is-merged /boot /dev /etc /home /init /lib /lib.usr-is-merged /lib64 /lost+found /media /mnt /opt /proc /root /run /sbin /sbin.usr-is-merged /snap /srv /sys /tmp /usr /var LiteOn WN4516R module, nonstandard USB connector linux/ { USB_DEVICE(0x0471, 0x7600) }, /bin /bin.usr-is-merged /boot /dev /etc /home /init /lib /lib.usr-is-merged /lib64 /lost+found /media /mnt /opt /proc /root /run /sbin /sbin.usr-is-merged /snap /srv /sys /tmp /usr /var LiteOn WN4519R module, nonstandard USB connector linux/ ``` - **Risk**: Minimal - adding device IDs is very safe - **Impact**: Enables support for new hardware without affecting existing devices - **Scope**: Contained to device identification ### 2. VHT Capability Fix (Critical Bug Fix) ```c switch (dev->mt76.rev) { case 0x76320044: /bin /bin.usr- is-merged /boot /dev /etc /home /init /lib /lib.usr-is-merged /lib64 /lost+found /media /mnt /opt /proc /root /run /sbin /sbin.usr-is-merged /snap /srv /sys /tmp /usr /var these ASIC revisions do not support VHT linux/ vht = false; break; default: vht = true; break; } ``` - **Fixes critical connectivity issues**: The commit explicitly fixes 5G connectivity problems - **Hardware-specific workaround**: Targets a specific ASIC revision (0x76320044) - **Conservative approach**: Disables problematic VHT only for affected hardware - **Minimal regression risk**: Existing devices continue using VHT as before ## Backport Suitability Criteria ✅ **Fixes user-affecting bugs**: Resolves 5G connectivity issues on LiteOn modules and potentially XBox One adapters ✅ **Small and contained**: Changes are minimal - 2 new USB IDs and a targeted VHT disable ✅ **No architectural changes**: Uses existing framework, just adds device support and fixes capability detection ✅ **References external issues**: Links to GitHub issues #971 and #200, indicating real user problems ✅ **Clear side effects documentation**: VHT disabling is well-documented and justified with FCC information ✅ **Follows stable tree rules**: Important hardware support fix with minimal regression risk ✅ **Confined to subsystem**: Changes limited to mt76x2 USB driver ## Hardware Impact Assessment The commit addresses **confirmed hardware limitations** where VHT was incorrectly enabled on chipsets that don't support it, causing: - Connection failures in 5GHz band - Potential instability when VHT features are attempted This matches the pattern of **Similar Commit #1** which added support for newer XBox One adapters and was successfully backported. The risk/benefit ratio strongly favors backporting: minimal code changes that fix real connectivity issues for specific hardware without affecting other devices.
drivers/net/wireless/mediatek/mt76/mt76x2/usb.c | 2 ++ .../net/wireless/mediatek/mt76/mt76x2/usb_init.c | 13 ++++++++++++- 2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2/usb.c b/drivers/net/wireless/mediatek/mt76/mt76x2/usb.c index d804309992196..229a365370ef5 100644 --- a/drivers/net/wireless/mediatek/mt76/mt76x2/usb.c +++ b/drivers/net/wireless/mediatek/mt76/mt76x2/usb.c @@ -17,6 +17,8 @@ static const struct usb_device_id mt76x2u_device_table[] = { { USB_DEVICE(0x057c, 0x8503) }, /* Avm FRITZ!WLAN AC860 */ { USB_DEVICE(0x7392, 0xb711) }, /* Edimax EW 7722 UAC */ { USB_DEVICE(0x0e8d, 0x7632) }, /* HC-M7662BU1 */ + { USB_DEVICE(0x0471, 0x2126) }, /* LiteOn WN4516R module, nonstandard USB connector */ + { USB_DEVICE(0x0471, 0x7600) }, /* LiteOn WN4519R module, nonstandard USB connector */ { USB_DEVICE(0x2c4e, 0x0103) }, /* Mercury UD13 */ { USB_DEVICE(0x0846, 0x9053) }, /* Netgear A6210 */ { USB_DEVICE(0x045e, 0x02e6) }, /* XBox One Wireless Adapter */ diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2/usb_init.c b/drivers/net/wireless/mediatek/mt76/mt76x2/usb_init.c index 33a14365ec9b9..3b55628115115 100644 --- a/drivers/net/wireless/mediatek/mt76/mt76x2/usb_init.c +++ b/drivers/net/wireless/mediatek/mt76/mt76x2/usb_init.c @@ -191,6 +191,7 @@ int mt76x2u_register_device(struct mt76x02_dev *dev) { struct ieee80211_hw *hw = mt76_hw(dev); struct mt76_usb *usb = &dev->mt76.usb; + bool vht; int err;
INIT_DELAYED_WORK(&dev->cal_work, mt76x2u_phy_calibrate); @@ -217,7 +218,17 @@ int mt76x2u_register_device(struct mt76x02_dev *dev)
/* check hw sg support in order to enable AMSDU */ hw->max_tx_fragments = dev->mt76.usb.sg_en ? MT_TX_SG_MAX_SIZE : 1; - err = mt76_register_device(&dev->mt76, true, mt76x02_rates, + switch (dev->mt76.rev) { + case 0x76320044: + /* these ASIC revisions do not support VHT */ + vht = false; + break; + default: + vht = true; + break; + } + + err = mt76_register_device(&dev->mt76, vht, mt76x02_rates, ARRAY_SIZE(mt76x02_rates)); if (err) goto fail;