On Wed, 2020-05-27 at 15:16 +0200, Joakim Tjernlund wrote: > On Wed, 2020-05-27 at 12:41 +0200, Oliver Neukum wrote: > > Am Mittwoch, den 27.05.2020, 09:40 +0000 schrieb Joakim Tjernlund: > > > On Wed, 2020-05-27 at 10:38 +0200, Oliver Neukum wrote: > > > > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe. > > > > > > > > > > > > Am Dienstag, den 26.05.2020, 17:19 +0000 schrieb Joakim Tjernlund: > > > > > This "u-boot SPL" is the first thing u-boot writes and somehow this is remembered, I assume, by cdc_acm > > > > > and gets echoed back when I open ttyACM0 > > > > > > > > Hi, > > > > > > > > that makes sense, but it is not something that we could really > > > > change in CDC-ACM, I am afraid. > > > > > > Why not? CDC-ACM should echo back anything it has received before open of ttyACM > > > > Well, there is an inherent race condition with loading the module I am > > afraid. By default cdc-acm should actually echo. You can set the > > DISABLE_ECHO echo quirk for your device if you want to get rid of it. > > > > Is CDC-ACM violating some standard with respect to echoing? Changing > > defaults really hurts users, no matter what you do. > > > > /* > * Suppress initial echoing for some devices which might send data > * immediately after acm driver has been installed. > */ > if (acm->quirks & DISABLE_ECHO) > tty->termios.c_lflag &= ~ECHO; > > That seems to be what I needed, should be default I think ... > Need to test som more but looks much better. > I guess all cdc_acm's are could suffer from this? Will depend the target in the other > end. > Would be nice if the ECHO could be delay until first read(2)/termios_set, the baudrate could be 11500 until open(2) too, maybe However, the bigger question: Is the a way to configure Windows to default to ~ECHO too ? Jocke