Hey all, I wanted to send these out for comment and thoughts.
Since ~4.20, when the functionfs gadget enabled scatter-gather support, we have seen problems with adb connections stalling and stopping to function on hardware with dwc3 usb controllers. Specifically, HiKey960, Dragonboard 845c, and Pixel3 devices.
Any chance this:
https://git.kernel.org/pub/scm/linux/kernel/git/balbi/usb.git/commit/ ?h=testing/next&id=f63333e8e4fd63d8d8ae83b89d2c38cf21d64801
This is a different issue. I have tried initializing num_sgs when debugging this adb stall problem, but it didn't help.
So multiple folks have run through this problem, but not *one* has tracepoints collected from the issue? C'mon guys. Can someone, please, collect tracepoints so we can figure out what's actually going on?
I'm pretty sure this should be solved at the DMA API level, just want to confirm.
I have sent you the tracepoints long time ago. Also my analysis of the problem (BTW, I don't think the tracepoints helped much). It's basically a logic problem in function dwc3_gadget_ep_reclaim_trb_sg(). I can try dig into my old emails and resend, but that is a bit hard to find.
-Fei