I have 1 Full Speed (12 Mbps) CDC-ACM type USB device connected directly to a High Speed (EHCI - 480 Mbps) controller on a SoC.
When there is no user-space application opening the CDC-ACM device in linux, I see a pulse which is repeated every 1 ms (SOF). Once an application (example cat) opens the CDC-ACM device, I see a lot of IN tokens (~102) between 2 SOF's from the host and the device NAKs the IN token. We are suspecting the device is busy NAKing that it hampers its operation.
Q1: Is there a way to reduce the number of IN tokens within the 1 ms interval?
Thanks
0_l_0