[Nut-upsuser] blazer_usb and USBDEVFS_CONTROL failed

[Charles Lepple]

On Nov 25, 2013, at 4:56 PM, Fabio Cecamore wrote:

> Hi all,
> after a change of UPS (to Atlantis Host Power 851) I began to use the new driver blazer_usb and compared to old one (blazer used with serial connection) I noted more CPU use and errors in dmesg:
> 
> [...]
> [256712.584370] usb 4-5: usbfs: USBDEVFS_CONTROL failed cmd blazer_usb rqt 33 rq 9 len 8 ret -110

"ret -110" is a timeout, I believe.

> Obviously the usb ports work good, I think is a bug in the driver or something like..

Could be a cable problem, too.

What version of NUT? We increased the timeout in 2.7.1.

Also, devices that talk to blazer_usb are basically serial UPSes with a USB-to-serial converter. The increased CPU usage is not surprising, since the host now has to poll the USB-to-serial converter (rather than the UART interrupting the CPU when data is ready). Do you have any profiling data to show how much more CPU time is being used?

-- 
Charles Lepple
clepple at gmail