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Subject: Re: [REGRESSION] usb: gadget: f_fs: Allow scatter-gather buffers
To:     John Stultz <john.stultz@linaro.org>
Cc:     Felipe Balbi <balbi@kernel.org>, "Yang, Fei" <fei.yang@intel.com>,
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From:   Andrzej Pietrasiewicz <andrzej.p@collabora.com>
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Date:   Mon, 13 May 2019 16:08:41 +0200
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Hi John,

W dniu 09.05.2019 o 23:23, John Stultz pisze:
> On Thu, May 9, 2019 at 11:25 AM John Stultz <john.stultz@linaro.org> wrote:
>>
>> On Thu, May 9, 2019 at 7:02 AM Andrzej Pietrasiewicz
>> <andrzej.p@collabora.com> wrote:
>>>

<snip>

> 
> 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:

5acb4b970184d189d901192d075997c933b82260
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?

Andrzej