Re: Raspberry Pi 3B USB Printing Issue

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