wfjm.w11

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History

wfjm c4f33e1c9d Update USB serial latency handling

- 99-retro-usb-permissions.rules renamed to 90-retro-usb-permissions.rules
- 91-retro-usb-latency.rules: udev rule to enforce low latency for FDTI USB UART
- 92-retro-usb-persistent.rules: udev rule for persistent device names
- Note:
  - for all FTDI USB-UART it is essential to set them to `low latency` mode.
    That was default for linux kernels 2.6.32 to 4.4.52. Since about March
    2017 one gets kernels with 16 ms default latency again, thanks to
    kernel patch 9589541. For newer systems it is essential to install the
    udev rule which automatically sets low latency.

2017-06-03 16:23:55 +02:00

90-retro-usb-permissions.rules

Update USB serial latency handling

2017-06-03 16:23:55 +02:00

README.md

Update USB serial latency handling

2017-06-03 16:23:55 +02:00

README.md

This directory contains udev rules which ensure that the Cypress FX2 on

Digilent Nexys2
Digilent Nexys3
Digilent Atlys

is read/write accessible for user land processes, either in

original power on state (thus Digilent VID/PID)
after custom firmware is loaded (thus VOTI VID/PID)

The rules assume that eligible user accounts are in group plugdev.
Check with the groups command whether your account is in group plugdev,
in not, add this group to your accounts groups list.

To setup udev rules do

    sudo cp -a 90-retro-usb-permissions.rules /etc/udev/rules.d/
    sudo chown root:root /etc/udev/rules.d/90-retro-usb-permissions.rules
    dir /etc/udev/rules.d/

    sudo udevadm control --reload-rules

to verify whether usb device was really put into group plugdev

  lsusb
    # --> look for bus/dev of interest

  find /dev/bus/usb -type c | sort| xargs ls -l
    # --> check whether bus/dev of interest is in group plugdev