On Monday 8 May 2017, at 17:38, Johan Hovold wrote: > You can read (and also change) the latency-timer value used through > sysfs: > > # cat /sys/bus/usb-serial/devices/ttyUSB0/latency_timer > 16 > > if that's what you needed? But unless you change it, you can infer the > value to be either 16 (default) or 1 depending on if ASYNC_LOW_LATENCY > is set as indicated by TIOCGSERIAL. Yes, but the sysfs path has a lots a drawbacks: - 666 permissions by default, so unprivileged users cannot change it - if ASYNC_LOW_LATENCY is not set, the current latency value cannot be infered (it could have been changed from the default, by e.g. a udev rule). - I don't know any way to guess the sysfs path from a tty device path, at least not without requiring a lot of extra dependencies and very linux-specific code. This is all the more complex if you consider that the tty path can either be a pty, a ftdi_sio tty or anything else provided that isatty(3) returns 1 ... -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
