Message-ID: <ff6d7385-a6d7-8920-dbe6-9018432392fa@synopsys.com>
Date:   Thu, 26 Aug 2021 01:18:20 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Ferry Toth <fntoth@...il.com>,
        Pavel Hofman <pavel.hofman@...tera.com>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>
CC:     Felipe Balbi <balbi@...nel.org>,
        Wesley Cheng <wcheng@...eaurora.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "agross@...nel.org" <agross@...nel.org>,
        "bjorn.andersson@...aro.org" <bjorn.andersson@...aro.org>,
        "frowand.list@...il.com" <frowand.list@...il.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
        "jackp@...eaurora.org" <jackp@...eaurora.org>,
        "heikki.krogerus@...ux.intel.com" <heikki.krogerus@...ux.intel.com>,
        Ruslan Bilovol <ruslan.bilovol@...il.com>
Subject: Re: [PATCH v10 0/6] Re-introduce TX FIFO resize for larger EP
 bursting

Ferry Toth wrote:
> 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@...tera.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 :-)
> 

Ferry can correct me if I'm wrong, but I think Edison-Arduino kit only
supports up to highspeed. Regardless, Edison-Arduino seems to work well
with the latest Linux kernel.

I see that there are various development kits with rk3399 that supports
up to SuperSpeed at reasonable price, but I think they all require some
effort to bring up to the latest Linux kernel and in device mode.

Maybe Ferry/Felipe/anyone can provide more recommendations?

Thanks,
Thinh

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