On Mon, May 31, 2021 at 05:33:02PM +0300, Andy Shevchenko wrote:
> 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!
Care to send the revert?
thanks,
greg k-h
