Re: Raspberry Pi 3B USB Printing Issue

On 3/14/22 10:20, Archimedes Gaviola wrote:
> On Sun, Mar 13, 2022 at 11:25 PM Archimedes Gaviola <
> archimedes.gaviola@gmail.com> wrote:
> 
>>
>>
>> On Sun, Mar 13, 2022 at 2:27 PM Archimedes Gaviola <
>> archimedes.gaviola@gmail.com> wrote:
>>
>>>
>>>
>>> On Sun, Mar 13, 2022 at 12:38 AM Hans Petter Selasky <hps@selasky.org>
>>> wrote:
>>>
>>>> On 3/12/22 16:31, Archimedes Gaviola wrote:
>>>>>>
>>>>>> IOERROR usually means an electrical error. The RPI3B will use a
>>>>>> transaction translator for the FULL speed traffic, which is driven by
>>>>>> software.
>>>>>
>>>>
>>>> Hi Archimedes,
>>>>
>>>>> Hi Hans,
>>>>>
>>>>> I'm curious about the transaction translator you've mentioned, any
>>>> idea why
>>>>> there's a need for translation and what is being translated?
>>>>
>>>> When the High Speed USB HUB was invented, there was a need to support
>>>> FULL and LOW speed USB transactions. Because FULL and LOW speed
>>>> transactions are slow and take up much bandwidth, a transactions
>>>> translator was invented which translates between High Speed USB and
>>>> FULL/LOW speed USB. That means the RPi 3B consists of a single USB HIGH
>>>> speed port, followed by a USB HUB. These transactions are not visible in
>>>> usbdump .
>>>>
>>>>   >Does this only
>>>>> happen when RPi 3B (acting as host controller) is transmitting data to
>>>> the
>>>>> Epson printer? Are translation events visible in the usbdump? In this
>>>> case
>>>>> there's a way to possibly track what's going on and how to identify any
>>>>> info that is being translated?
>>>>
>>>> By turning on the HC debugging, you can possibly track via debug
>>>> messages what is going on. Maybe it is a timing issue, that the SW is
>>>> too slow serving the micro transactions.
>>>>
>>>> Any idea also if translation is being
>>>>> performed in RPi 4B?
>>>>
>>>> The later RPi's do the transaction translator bits in HW or via the XHCI
>>>> block.
>>>>
>>>> As I have conducted several printing cases with my
>>>>> Epson printer without any issues with either of the 4 ports.
>>>>>
>>>>> Sorry for these questions as I am catching-up to the USB technology
>>>>> internal workings under the hood.
>>>>
>>>> You are welcome!
>>>>
>>>
>>>
>>> Thank you so much Hans for answering my questions, really appreciate it!
>>> I have a much better understanding now.
>>>
>>> I came from testing with 13.0-RELEASE having the same RPi 3B hardware and
>>> setup and it's very stable. I haven't encountered any IOERROR and
>>> incomplete printed outputs that were encountered with 14.0-CURRENT
>>> (February 24, 2022). By the way, I found in the repository here
>>> https://download.freebsd.org/snapshots/arm64/aarch64/ISO-IMAGES/14.0/
>>> that there were two latest snapshots released dated March 3 and March 10,
>>> respectively. I need to take printing tests first, especially the latest to
>>> check if it also manifests before I go back to the Feb. 24 snapshot and do
>>> a thorough test with debugging. I'll provide updates for any observations.
>>>
>>> Thanks,
>>> Archimedes
>>>
>>
>>
>> Hi Hans,
>>
>> Initial testing conducted with the latest 14.0-CURRENT (March 10, 2022
>> snapshot) seems to be stable. Another test will be performed tomorrow.
>>
>> Thanks,
>> Archimedes
>>
> 
> Hi Hans,
> 
> I still encountered the issue this morning with 14.0-CURRENT (March 10,
> 2022 snapshot). I just noticed when I left my RPi 3B idle for a long period
> of time (2-3 hours and more) and started printing, then the issue pops-up.
> Another concern I encountered was when I started enabling
> hw.usb.dwc_otg.debug but after 1-2 minutes my USB keyboard and network
> interface (remotely connected over SSH from my laptop) seemed to freeze and
> I got disconnected.
> 
> freebsd@generic:~ % uname -a
> FreeBSD generic 14.0-CURRENT FreeBSD 14.0-CURRENT #0
> main-n253697-f1d450ddee6: Thu Mar 10 09:32:38 UTC 2022
> root@releng1.nyi.freebsd.org:/usr/obj/usr/src/arm64.aarch64/sys/GENERIC
> arm64
> 
> root@generic:~ # sysctl -w hw.usb.dwc_otg.debug=1
> hw.usb.dwc_otg.debug: 0 -> 1
> 
> See attached initial debug info (no printing testing yet).

Hi,

Nothing obvious there.

Maybe you need to add a conditional to DPRINTF's in the fast path, to 
only print for a certain device, to reduce the debug prints.

How many USB devices are connected?

One experiment you might try is to comment out:

usbd_transfer_submit(xfer);

in

uhub_intr_callback()

in

/usr/src/sys/dev/usb/usb_hub.c

It will save some USB resources, but also makes USB enumeration a bit 
slower. Maybe the chip is out of USB HW endpoints and is only polling 
for RX data ...

--HPS