On Wed, May 27, 2015 at 02:48:18PM -0000, Karl Palsson wrote: > > Hi, > > I've been using OpenWrt's "usb activity" led trigger to display > usb-serial traffic over a cp210x dongle quite successfully, but after > replacing the cp210x with a FT230x, I find that I get constant USB > traffic (every millisecond) as soon as the port is opened. > It's important to note that /dev/ttyUSB0 still _works_ I just get > substantially more usb traffic than I expect. I do _not_ see this level > of traffic with any FT232RL devices or cp210x devices, though, > unfortunately, I can't test those with the same hardware. The FT230x is > permanently connected to a SMSC USB2640 hub on a custom board. I also > don't have a FT230x I can try on my desktop linux either at this stage. > :( > > This is seen with kernel 3.18.12, but was originally seen with 3.10.49. > I can't see anything in the ftdio_sio driver other than new VID/PIDs > since 3.18, so I haven't tried anything newer. > > The usbmon traces seem to be a continual reporting of the "0x0160" shown > in the ftdi_get_modem_status lines. Is this actually _meant_ to be > happening? Can I turn it off? Any other suggestions? This is the device reporting the modem and line status every millisecond. You can increase the interval by clearing the low_latency flag and setting a even higher value than the otherwise default 16ms period through sysfs. Note that this also means that any data received will not necessarily be forwarded every millisecond either anymore. Johan -- 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
