Re: [REGRESSION] usb: gadget: f_fs: Allow scatter-gather buffers

From: Andrzej Pietrasiewicz
Date: Mon May 13 2019 - 10:10:19 EST

Hi John,

W dniu 09.05.2019 oÂ23:23, John Stultz pisze:
On Thu, May 9, 2019 at 11:25 AM John Stultz <john.stultz@xxxxxxxxxx> wrote:

On Thu, May 9, 2019 at 7:02 AM Andrzej Pietrasiewicz
<andrzej.p@xxxxxxxxxxxxx> wrote:


Ok. Apologies for earlier confusion.

So the kzalloc/memset fix you sent for f_fs.c does seem to avoid the
crash on bootup I was seeing w/ HiKey/dwc2 (previously I had only
tested it on HiKey960/dwc3).

However with that patch, I still see tranfer problems with adb, unless
I comment out setting sg_supported in dwc2/gadget.c (in the same
fashion I have to with HiKey960/dwc3).

The dwc2 zlp patch doesn't seem to affect things much either way in my
testing. But maybe I'm just not tripping on that issue yet.

So yes, the kzalloc/memset patch is a clear improvement, as it avoids
the bootup crash on dwc2, and seems like it should go in.

However, there is still the outstanding issue w/ functionfs sg
support stalling on larger transfers.

Do you get "functionfs read size 512 > requested size 24, splitting
request into multiple reads" message when problems happen?

Is there anything in the kernel log?

I'm unable to reproduce your problems. I thought I was able, but
it was another problem, which is fixed with:

dwc2: gadget: Fix completed transfer size calculation in DDMA

(or you can simply take upstream drivers/usb/dwc2).

Do your problems happen on dwc2 or dwc3?

Is there a way to try your adb without building and running the
whole Android?