Running no any other application under Linux. the Max3421 driver uses to 25%-27% CPU time. (Host mode).
When running a graphical app, when a device is plugged in the performance impact is visible in stuttering of the graphics rendering.
The stuttering does not happen when there are no USB devices connected to it.
What could be root causes for this ? Could it be poor signal quality ?
The USB device itself is doing nothing.
We use the Keyes board with MAX3421 and run it at max 12MHz . it is connected with some wires to a SPI header on the embedded board.
connected USB devices themselves run fine.
Sometimes when a device is connected, Linux prompt many messages such as , after a while this may stop.
306.624318] hub 3-0:1.0: hub_suspend
[ 306.703367] hub 1-0:1.0: hub_resume
[ 306.705707] hub 1-0:1.0: state 7 ports 2 chg 0000 evt 0000
[ 306.719144] hub 1-0:1.0: hub_suspend
[ 306.922223] hub 4-0:1.0: state 7 ports 1 chg 0000 evt 0002
[ 306.926641] usb usb4-port1: status 0101, change 0001, 12 Mb/s
[ 306.968361] hub 2-0:1.0: hub_resume
[ 306.970610] hub 2-0:1.0: state 7 ports 1 chg 0000 evt 0000
[ 306.985082] hub 2-0:1.0: hub_suspend
[ 307.280638] usb usb4-port1: debounce total 175ms stable 100ms status 0x100
[ 307.286746] hub 3-0:1.0: hub_resume
[ 307.289878] usb usb3-port1: status 0507 change 0000
[ 307.300580] hub 3-0:1.0: state 7 ports 2 chg 0000 evt 0000
[ 307.305033] usb 3-1: usb auto-resume
[ 307.390123] usb 3-1: Waited 0ms for CONNECT
[ 307.393438] usb 3-1: finish resume
[ 307.397568] hub 3-1:1.0: hub_resume
[ 307.407799] hub 3-1:1.0: state 7 ports 4 chg 0000 evt 0000
[ 307.413293] hub 3-1:1.0: hub_suspend
[ 307.418249] usb 3-1: usb auto-suspend, wakeup 1
[ 307.419942] hub 4-0:1.0: state 7 ports 1 chg 0000 evt 0002
[ 307.427345] usb usb4-port1: status 0100, change 0001, 12 Mb/s
[ 307.449813] hub 3-0:1.0: hub_suspend
[ 307.549392] hub 1-0:1.0: hub_resume
[ 307.551879] hub 1-0:1.0: state 7 ports 2 chg 0000 evt 0000
[ 307.565172] hub 1-0:1.0: hub_suspend
[ 307.629171] usb usb4-port1: debounce total 100ms stable 100ms status 0x100
[ 307.692639] hub 2-0:1.0: hub_resume
[ 307.695061] hub 2-0:1.0: state 7 ports 1 chg 0000 evt 0000
[ 307.709188] hub 2-0:1.0: hub_suspend
[ 307.714617] hub 3-0:1.0: hub_resume
[ 307.716820] usb usb3-port1: status 0507 change 0000
[ 307.727682] hub 3-0:1.0: state 7 ports 2 chg 0000 evt 0000
[ 307.736547] usb 3-1: usb auto-resume
[ 307.828114] usb 3-1: Waited 0ms for CONNECT
[ 307.830922] usb 3-1: finish resume
[ 307.835378] hub 3-1:1.0: hub_resume
[ 307.841310] hub 3-1:1.0: state 7 ports 4 chg 0000 evt 0000
[ 307.847105] hub 3-1:1.0: hub_suspend
[ 307.851916] usb 3-1: usb auto-suspend, wakeup 1
[ 307.887920] hub 3-0:1.0: hub_suspend
[ 307.927766] hub 4-0:1.0: state 7 ports 1 chg 0000 evt 0002
[ 307.932145] usb usb4-port1: status 0100, change 0001, 12 Mb/s
[ 307.958175] hub 1-0:1.0: hub_resume
[ 307.960498] hub 1-0:1.0: state 7 ports 2 chg 0000 evt 0000
[ 307.975480] hub 1-0:1.0: hub_suspend
[ 307.993972] systemd-journald[315]: Data hash table of /run/log/journal/d649c09102144cf38944c92ea4dba7d8/system.journal has a fill level at 75.0 (10923 of 14563 items, 8388608 file size, 767 bytes per hash table item), suggesting rotation.
[ 308.021853] systemd-journald[315]: /run/log/journal/d649c09102144cf38944c92ea4dba7d8/system.journal: Journal header limits reached or header out-of-date, rotating.
[ 308.319526] hub 2-0:1.0: hub_resume
[ 308.321908] hub 2-0:1.0: state 7 ports 1 chg 0000 evt 0000
[ 308.336125] usb usb4-port1: debounce total 200ms stable 100ms status 0x101
[ 308.342367] hub 2-0:1.0: hub_suspend
[ 308.415785] usb usb4-port1: not reset yet, waiting 60ms
[ 308.495579] usb usb4-port1: not reset yet, waiting 200ms
[ 308.714632] usb usb4-port1: not reset yet, waiting 200ms
[ 308.933841] usb usb4-port1: not reset yet, waiting 200ms
