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From:   Ferry Toth <fntoth@gmail.com>
Subject: Re: [PATCH v10 0/6] Re-introduce TX FIFO resize for larger EP
 bursting
To:     Pavel Hofman <pavel.hofman@ivitera.com>,
        Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
        Andy Shevchenko <andy.shevchenko@gmail.com>
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Message-ID: <84236328-750e-700a-855b-19b362362d25@gmail.com>
Date:   Tue, 24 Aug 2021 15:44:40 +0200
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Hi

Op 24-08-2021 om 07:39 schreef Pavel Hofman:
>
>
> Dne 24. 08. 21 v 0:50 Thinh Nguyen napsal(a):
>> Pavel Hofman wrote:
>>>
>>>
>>> Dne 23. 08. 21 v 17:21 Andy Shevchenko napsal(a):
>>>> On Mon, Aug 23, 2021 at 5:59 PM Pavel Hofman
>>>> <pavel.hofman@ivitera.com> wrote:
>>>>> Dne 22. 08. 21 v 21:43 Ferry Toth napsal(a):
>>>>>> Op 19-08-2021 om 23:04 schreef Pavel Hofman:
>>>>>>> Dne 19. 08. 21 v 22:10 Ferry Toth napsal(a):
>>>>>>>> Op 19-08-2021 om 09:51 schreef Pavel Hofman:
>>>>>>>>> Dne 18. 08. 21 v 21:07 Ferry Toth napsal(a):
>>>>>>>>>> Op 18-08-2021 om 00:00 schreef Ferry Toth:
>>>>
>>>> ...
>>>>
>>>>>>>>>> So, where do we go from here?
>>>>>>>>>
>>>>>>>>> I know the patches have been tested on dwc2 (by me and 
>>>>>>>>> others).  I
>>>>>>>>> do not know if Ruslan or Jerome tested them on dwc3 but probably
>>>>>>>>> not. Ruslan has talked about RPi (my case too) and 
>>>>>>>>> BeagleboneBlack,
>>>>>>>>> both with dwc2. Perhaps the dwc2 behaves a bit differently than
>>>>>>>>> dwc3?
>>>>>>>>>
>>>>>>>>> The patches add a new EP-IN for async feedback. I am sorry I have
>>>>>>>>> not followed your long thread (it started as unrelated to 
>>>>>>>>> uac). Does
>>>>>>>>> the problem appear with f_uac1 or f_uac2? Please how have you
>>>>>>>>> reached the above problem?
>>>>>>>>
>>>>>>>> I'm sorry too. I first believed the issue was related to the patch
>>>>>>>> mentioned in the subject line.
>>>>>>>>
>>>>>>>> The problem appaers with f_uac2. I bost Edison_Arduino board in 
>>>>>>>> host
>>>>>>>> mode (there is a switch allowing to select host/device mode). When
>>>>>>>> flipping the switch to device mode udev run a script:
>>>>>>>> But as I am using configfs (excerpt follows) and just disabling 
>>>>>>>> the
>>>>>>>> last 2 line resolves the issue, I'm guessing uac2 is the issue. Or
>>>>>>>> exceeding the available resources.
>>>>>>>>
>>>>>>>> # Create directory structure
>>>>>>>> mkdir "${GADGET_BASE_DIR}"
>>>>>>>> cd "${GADGET_BASE_DIR}"
>>>>>>>> mkdir -p configs/c.1/strings/0x409
>>>>>>>> mkdir -p strings/0x409
>>>>>>>>
>>>>>>>> # Serial device
>>>>>>>> mkdir functions/gser.usb0
>>>>>>>> ln -s functions/gser.usb0 configs/c.1/
>>>>>>>> ###
>>>>>>>>
>>>>>>>> # Ethernet device
>>>>>>>> mkdir functions/eem.usb0
>>>>>>>> echo "${DEV_ETH_ADDR}" > functions/eem.usb0/dev_addr
>>>>>>>> echo "${HOST_ETH_ADDR}" > functions/eem.usb0/host_addr
>>>>>>>> ln -s functions/eem.usb0 configs/c.1/
>>>>>>>>
>>>>>>>> # Mass Storage device
>>>>>>>> mkdir functions/mass_storage.usb0
>>>>>>>> echo 1 > functions/mass_storage.usb0/stall
>>>>>>>> echo 0 > functions/mass_storage.usb0/lun.0/cdrom
>>>>>>>> echo 0 > functions/mass_storage.usb0/lun.0/ro
>>>>>>>> echo 0 > functions/mass_storage.usb0/lun.0/nofua
>>>>>>>> echo "${USBDISK}" > functions/mass_storage.usb0/lun.0/file
>>>>>>>> ln -s functions/mass_storage.usb0 configs/c.1/
>>>>>>>>
>>>>>>>> # UAC2 device
>>>>>>>> mkdir functions/uac2.usb0
>>>>>>>> ln -s functions/uac2.usb0 configs/c.1
>>>>>>>> ....
>>>>>>>
>>>>>>> As you say, could perhaps the reason be that the extra EP-IN 
>>>>>>> added in
>>>>>>> those patches (previously 1, now 2 with the default config you use)
>>>>>>> exceeds your EP-IN max count or available fifos somehow?  You 
>>>>>>> have a
>>>>>>> number of functions initialized. If you change the load order of 
>>>>>>> the
>>>>>>> functions, do you get the error later with a different function? 
>>>>>>> Just
>>>>>>> guessing...
>>>>>>>
>>>>>>> You should be able to switch the default async EP-OUT (which
>>>>>>> configures the new feedback EP-IN ) to adaptive EP-OUT (which 
>>>>>>> requires
>>>>>>> no feedback EP) with c_sync=8 parameter of f_uac2.
>>>>>>>
>>>>>>> https://urldefense.com/v3/__https://elixir.bootlin.com/linux/v5.14-rc6/source/drivers/usb/gadget/function/f_uac2.c*L47__;Iw!!A4F2R9G_pg!LBySrM_zgMGV0x-zZ7nSrs54yJw1GlnpUVUVxdQE8PeszSMZ6OkFX8lSoigwRbWQzLcU$ 
>>>>>>>
>>>>>>>
>>>>>>> https://urldefense.com/v3/__https://elixir.bootlin.com/linux/v5.14-rc6/source/drivers/usb/gadget/function/f_uac2.c*L830__;Iw!!A4F2R9G_pg!LBySrM_zgMGV0x-zZ7nSrs54yJw1GlnpUVUVxdQE8PeszSMZ6OkFX8lSoigwRfP5TdZC$ 
>>>>>>>
>>>>>>>
>>>>>>> https://urldefense.com/v3/__https://elixir.bootlin.com/linux/v5.14-rc6/source/include/uapi/linux/usb/ch9.h*L453__;Iw!!A4F2R9G_pg!LBySrM_zgMGV0x-zZ7nSrs54yJw1GlnpUVUVxdQE8PeszSMZ6OkFX8lSoigwRejzMbWO$ 
>>>>>>>
>>>>>>>
>>>>>>> Does that fix the problem?
>>>>>>
>>>>>> Not sure how to do that. Do you mean the module should have a 
>>>>>> parameter
>>>>>> called c_sync? `modinfo` list no parameters for usb_f_uac2.
>>>>>
>>>>> Those are configfs params, not available in modinfo.
>>>>>
>>>>> I checked and the value is "adaptive"
>>>>> https://urldefense.com/v3/__https://elixir.bootlin.com/linux/v5.14-rc7/source/drivers/usb/gadget/function/f_uac2.c*L1312__;Iw!!A4F2R9G_pg!LBySrM_zgMGV0x-zZ7nSrs54yJw1GlnpUVUVxdQE8PeszSMZ6OkFX8lSoigwRTETcbsN$ 
>>>>>
>>>>
>>>>
>>>>> In your configfs script:
>>>>
>>>> Kernel shouldn't crash with any available set of configuration
>>>> parameters, right? So, even if the parameter would fix the crash the
>>>> series is buggy and has to be reverted in my opinion.
>>>
>>> Sure, no problem with reverting. I am just trying to start up some
>>> troubleshooting. A resource exhaustion was mentioned here, that's why I
>>> suggested a way to test the patch with the original number of endpoints
>>> allocated. I do not get any crashes on my setup which uses fewer gadget
>>> functions. That's why I asked what happens if the functions load order
>>> is changed. I am afraid this thread is so complex that the actual
>>> problem has been burried in the history.
>>>
>>
>> As I pointed out previously, the crash is probably because of f_uac2
>> prematurely freeing feedback request before its completion.
>> usb_ep_dequeue() is asynchronous. dwc2() may treat it as a synchronous
>> call so you didn't get a crash.
>
> Thanks for your hint, it greatly helps.
>>>
>>
>> I'm not sure how easy it is for you to obtain/test a device with dwc3,
>> but it would be great to also have it as part of your testing suite. :)
>
> Can you recommend a reasonably priced device with viable kernel 
> updates for the testing? Optionally with SS which you mentioned last 
> time? Thanks.
>
Edison-Arduino kit 2nd hand with display on ebay ~$100 :-)

> Best regards,
>
> Pavel.