Kernel Bug Tracker – Bug 9120
sysfs latency_timer for FT232RL chip
Last modified: 2009-06-02 14:39:27 UTC
Most recent kernel where this bug did not occur: 188.8.131.52, maybe later versions (could not check)
Hardware Environment: FTDI FT232RL based dongle for serial communication
The driver does not create the sysfs' latency_timer file for FT232RL chips (only for FT232BM and FT232C chips).
Older versions used to detect this same chip as a FT232BM compatible chip, and the latency_timer was correctly set.
Steps to reproduce:
insert a FT232RL based device on a USB plug.
This should be fixed in the 2.6.23-rc kernels, can you test there?
Maybe you forgot to change remove_sysfs_attrs ?
Do you see any incovenient on automagically set the latency_timer value to 2ms
(or anything around this), whenever the ASYNC_LOW_LATENCY flag is set on the
TIOCSSERIAL ioctl (set_serial_info)?
This would allow for a unified API with the "regular" UARTs, and people could
continue to use "setserial /dev/ttyUSB0 low_latency" instead of having to
fiddle around with sysfs params.