From e137e5fd245cb6c0ae378607cc8090c913d984b2 Mon Sep 17 00:00:00 2001 From: Sean Wang Date: Sat, 13 Jun 2026 17:41:28 -0500 Subject: [PATCH] wifi: mt76: mt792x: stop USB register access after bus hang Mark the mt792x USB bus hung on the first control timeout and switch register access to no-op bus ops. Each failed vendor request may spend up to MT_VEND_REQ_MAX_RETRY * MT_VEND_REQ_TOUT_MS, about 3 seconds, and teardown/reset paths can keep issuing such requests after the device has stopped responding. Also skip the USB WFSYS reset path after bus_hung is set, since it uses UHW vendor requests as well. mt7925u 1-2:1.3: vendor request req:63 off:0018 failed:-110 mt7925u 1-2:1.3: vendor request req:63 off:0018 failed:-110 mt7925u 1-2:1.3: vendor request req:63 off:0018 failed:-110 mt7925u 1-2:1.3: vendor request req:63 off:0018 failed:-110 mt7925u 1-2:1.3: vendor request req:63 off:0018 failed:-110 Avoid repeating those register reads after the bus is known to be hung by switching register access to no-op handlers. Fixes: 0d2afe09fad5 ("mt76: mt7921: add mt7921u driver") Fixes: c948b5da6bbe ("wifi: mt76: mt7925: add Mediatek Wi-Fi7 driver for mt7925 chips") Signed-off-by: Sean Wang Link: https://patch.msgid.link/20260613224131.2396026-4-sean.wang@kernel.org Signed-off-by: Felix Fietkau --- drivers/net/wireless/mediatek/mt76/mt76.h | 1 + .../net/wireless/mediatek/mt76/mt792x_usb.c | 91 ++++++++++++++++--- drivers/net/wireless/mediatek/mt76/usb.c | 11 +++ 3 files changed, 90 insertions(+), 13 deletions(-) diff --git a/drivers/net/wireless/mediatek/mt76/mt76.h b/drivers/net/wireless/mediatek/mt76/mt76.h index 6cff136407d8..640061276d76 100644 --- a/drivers/net/wireless/mediatek/mt76/mt76.h +++ b/drivers/net/wireless/mediatek/mt76/mt76.h @@ -672,6 +672,7 @@ struct mt76_usb { u8 out_ep[__MT_EP_OUT_MAX]; u8 in_ep[__MT_EP_IN_MAX]; + void (*ctrl_timeout)(struct mt76_dev *dev, int err); bool sg_en; struct mt76u_mcu { diff --git a/drivers/net/wireless/mediatek/mt76/mt792x_usb.c b/drivers/net/wireless/mediatek/mt76/mt792x_usb.c index 910132e94956..47f80c9ec4e7 100644 --- a/drivers/net/wireless/mediatek/mt76/mt792x_usb.c +++ b/drivers/net/wireless/mediatek/mt76/mt792x_usb.c @@ -31,10 +31,75 @@ static void mt792xu_reset_work(struct work_struct *work) atomic_set(&dev->usb_reset_pending, 0); } +static void mt792xu_queue_usb_reset(struct mt792x_dev *dev, int err) +{ + if (!atomic_xchg(&dev->usb_reset_pending, 1)) { + dev_warn(dev->mt76.dev, + "USB transport access failed (%d), queueing device reset\n", + err); + + schedule_work(&dev->usb_reset_work); + } +} + +static u32 mt792xu_bus_hung_rr(struct mt76_dev *mdev, u32 offset) +{ + return 0; +} + +static void mt792xu_bus_hung_wr(struct mt76_dev *mdev, u32 offset, u32 val) +{ +} + +static u32 mt792xu_bus_hung_rmw(struct mt76_dev *mdev, u32 offset, + u32 mask, u32 val) +{ + return 0; +} + +static void mt792xu_bus_hung_write_copy(struct mt76_dev *mdev, u32 offset, + const void *data, int len) +{ +} + +static void mt792xu_bus_hung_read_copy(struct mt76_dev *mdev, u32 offset, + void *data, int len) +{ + memset(data, 0, len); +} + +static const struct mt76_bus_ops mt792xu_bus_hung_ops = { + .rr = mt792xu_bus_hung_rr, + .wr = mt792xu_bus_hung_wr, + .rmw = mt792xu_bus_hung_rmw, + .write_copy = mt792xu_bus_hung_write_copy, + .read_copy = mt792xu_bus_hung_read_copy, + .type = MT76_BUS_USB, +}; + +static void mt792xu_set_bus_hung(struct mt792x_dev *dev) +{ + atomic_set(&dev->mt76.bus_hung, true); + + if (READ_ONCE(dev->mt76.bus) == &mt792xu_bus_hung_ops) + return; + + WRITE_ONCE(dev->mt76.bus, &mt792xu_bus_hung_ops); +} + +static void mt792xu_ctrl_timeout(struct mt76_dev *mdev, int err) +{ + struct mt792x_dev *dev = container_of(mdev, struct mt792x_dev, mt76); + + mt792xu_set_bus_hung(dev); + mt792xu_queue_usb_reset(dev, err); +} + void mt792xu_reset_work_init(struct mt792x_dev *dev) { INIT_WORK(&dev->usb_reset_work, mt792xu_reset_work); atomic_set(&dev->usb_reset_pending, 0); + dev->mt76.usb.ctrl_timeout = mt792xu_ctrl_timeout; } EXPORT_SYMBOL_GPL(mt792xu_reset_work_init); @@ -62,26 +127,23 @@ EXPORT_SYMBOL_GPL(mt792xu_check_bus); int mt792xu_reset_on_bus_error(struct mt792x_dev *dev) { - int err = 0; + int err; - if (!atomic_read(&dev->mt76.bus_hung)) - err = mt792xu_check_bus(dev); + /* Once hung, the no-op bus ops stay installed until the queued USB + * reset re-probes the device. Do not clear bus_hung here, or the caller + * would run a full reset over dropped register I/O and report success. + */ + if (atomic_read(&dev->mt76.bus_hung)) + return -EIO; + err = mt792xu_check_bus(dev); if (err) { - atomic_set(&dev->mt76.bus_hung, true); - - if (!atomic_xchg(&dev->usb_reset_pending, 1)) { - dev_warn(dev->mt76.dev, - "USB transport access failed (%d), queueing device reset\n", - err); - - schedule_work(&dev->usb_reset_work); - } + mt792xu_set_bus_hung(dev); + mt792xu_queue_usb_reset(dev, err); return err; } - atomic_set(&dev->mt76.bus_hung, false); return 0; } EXPORT_SYMBOL_GPL(mt792xu_reset_on_bus_error); @@ -344,6 +406,9 @@ int mt792xu_wfsys_reset(struct mt792x_dev *dev) u32 val; int i; + if (atomic_read(&dev->mt76.bus_hung)) + return -EIO; + mt792xu_epctl_rst_opt(dev, false); val = mt792xu_uhw_rr(&dev->mt76, desc->rst_reg); diff --git a/drivers/net/wireless/mediatek/mt76/usb.c b/drivers/net/wireless/mediatek/mt76/usb.c index e54b35e53b6a..a9af3aa6b80a 100644 --- a/drivers/net/wireless/mediatek/mt76/usb.c +++ b/drivers/net/wireless/mediatek/mt76/usb.c @@ -30,6 +30,8 @@ int __mt76u_vendor_request(struct mt76_dev *dev, u8 req, u8 req_type, for (i = 0; i < MT_VEND_REQ_MAX_RETRY; i++) { if (test_bit(MT76_REMOVED, &dev->phy.state)) return -EIO; + if (dev->usb.ctrl_timeout && atomic_read(&dev->bus_hung)) + return -EIO; ret = usb_control_msg(udev, pipe, req, req_type, val, offset, buf, len, MT_VEND_REQ_TOUT_MS); @@ -42,6 +44,15 @@ int __mt76u_vendor_request(struct mt76_dev *dev, u8 req, u8 req_type, dev_err(dev->dev, "vendor request req:%02x off:%04x failed:%d\n", req, offset, ret); + + if (dev->usb.ctrl_timeout) { + atomic_set(&dev->bus_hung, true); + dev_err(dev->dev, "vendor request req:%02x off:%04x timed out, marking bus hung\n", + req, offset); + dev->usb.ctrl_timeout(dev, ret); + return ret; + } + return ret; } EXPORT_SYMBOL_GPL(__mt76u_vendor_request);