Hi!
The only patch that made v5.13-rc4 effectively broke USB on Intel Merrifield.
My reproducer:
1. Boot with switch in gadget mode
2. Enable USB ethernet
3. Switch to host
4. wait a bit for device enumeration, etc
5. Switch back
6. No gadget mode, kernel RCU stall detected (USB become unusable, so
does the system)
[ 115.792620] rcu: INFO: rcu_sched self-detected stall on CPU
[ 115.798410] rcu: 0-....: (24089 ticks this GP)
idle=886/1/0x4000000000000000 softirq=3796/3797 fqs=5240
[ 115.808333] (t=21000 jiffies g=6505 q=12158)
[ 115.812847] NMI backtrace for cpu 0
[ 115.816472] CPU: 0 PID: 23 Comm: kworker/0:1 Not tainted 5.13.0-rc4+ #213
...
[ 115.977913] add_dma_entry+0xd4/0x1d0
[ 115.981760] dma_map_page_attrs+0xd8/0x220
[ 115.986063] usb_hcd_map_urb_for_dma+0x3b6/0x4f0
[ 115.990895] usb_hcd_submit_urb+0x98/0xbf0
[ 115.995263] dln2_rx+0x1ae/0x280 [dln2]
...
100% Reproducibility, revert of the 25dda9fc56bd ("usb: dwc3: gadget:
Properly track pending and queued SG") fixes the issue.
Please, fix it properly or revert. Thanks!
--
With Best Regards,
Andy Shevchenko
