On Mon, Dec 07, 2015 at 01:50:37PM +0000, Jose Colmenares wrote: > Hi, > > Well the amount of data is very small, about 16 floats plus a header in the > message. Lets round it up to 128 bytes. That means 128000 bytes per second > for a 1000Hz frequency (which the device can give). 128000 bytes per second > is a lot less than the 480 Mbps that USB 2 gives. That's what's killing me. > That in theory I should be able to do it, but the data arrives in bursts.
USB data comes in "bursts", sending small packets of data is just about the worst thing you can do on USB, sorry. You are also trying to abuse the cdc-acm driver for something it was not designed to do, why not use libusb and drive your device from userspace directly to get the data as fast as possible and avoid the tty layer (which isn't causing you problems, but would be good to get out of the way...) You can see the data on the "wire" as far as the kernel thinks it is coming in if you use usbmon, theres's documentation for it in the Documentation/usb/ directory of the kernel. That might help you see how bad your device really is in sending data at the rates you are expecting :) thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
