Re: [PATCH v6 0/2] usb: serial: add support for CH348

[David Heidelberg]

Hello Corentin,

is there chance you find some time to upstream this?
In the worst case I would try to find some time to look into this, so it 
would have chance to get merged.

Thanks
David

On 20/11/2023 13:29, Corentin LABBE wrote:
> Le Wed, Aug 30, 2023 at 07:43:03PM +0200, Nicolas Frattaroli a écrit :
> > On Mittwoch, 28. Juni 2023 15:38:32 CEST Corentin Labbe wrote:
> > > Hello
> > >
> > > The CH348 is an octo serial to USB adapter.
> > > The following patch adds a driver for supporting it.
> > > Since there is no public datasheet, unfortunatly it remains some magic values.
> > >
> > > It was tested with a large range of baud from 1200 to 1500000 and used with
> > > success in one of our kernel CI testlab.
> > >
> > > Regards
> > >
> > > [...]
> > Hello,
> >
> > thank you for your work on this. I recently made myself a CH348
> > board and used this patchset with a small test application[1]
> > to see how it performs. Specifically, I ran this on an RK3566
> > single board computer, connecting one serial adapter to the
> > other, with the test as follows:
> >
> >   ./serialtest /dev/ttyUSB0 9600 # UART0 of 1st CH348 board
> >   ./serialtest /dev/ttyUSB8 9600 # UART0 of 2nd CH348 board
> >
> > One problem I've noticed is that writes to the tty fd never
> > seem to block. On two CH340 adapters I have, they do seem to
> > block, whereas here, you can see from the statistics at the
> > end that magnitudes more bytes were written than read, with
> > seemingly most of them being discarded. From my reading of
> > the termios parameters I set, this shouldn't be the case,
> > right?
> >
> > You can see from the error percentage that it gets less
> > bad as you increase the serial baudrate; I've tested up
> > to 6 mbaud like this. I assume that's because less written
> > bytes get discarded.
> >
> > Any ideas on whether I'm relying on weird driver behaviour
> > with the blocking here or if this driver actually has a
> > defect whereby it never signals to userspace that less
> > bytes were written than have been submitted?
> >
> > Kind regards,
> > Nicolas Frattaroli
> >
> > [1]: https://github.com/CounterPillow/serialtest
> Hello
>
> Sorry for the very long delay of the answer.
> I have reproduced the problem on my board.
> My reproducer is https://github.com/montjoie/lava-tests/blob/master/test2a2.py
>
> This problem seems to be here since the v1 of my patchset.
> The vendor driver seems to work so it is not an hardware problem.
>
> I have no clue at the moment, it is hard to diff with vendor driver since it create tty directly and do not use usbserial.
>
> Regards

--
David Heidelberg