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
