RE: [RFC][PATCH 0/2] Avoiding DWC3 transfer stalls/hangs when using adb over f_fs

From: Felipe Balbi
Date: Thu Jan 23 2020 - 12:31:10 EST



Hi,

"Yang, Fei" <fei.yang@xxxxxxxxx> writes:
>>> 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.

cheers

--
balbi

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