Re: [libusb] Question - "libusb: error [winusbx_set_interface_altsetting] SetCurrentAlternateSetting failed: Insufficient system resources exist to complete the requested service."

[Tim R. <ti...@pr...>]

On 10/15/24 1:45 AM, Fourcade, Pierre wrote:

> Regarding the issue: “Randomly”, with our custom USB device, libusb 
> reports a systematic failure when attempting to set the device to a 
> specific alternate setting. When setting the log levels to debug, the 
> following issue is reported: “libusb: error 
> [winusbx_set_interface_altsetting] SetCurrentAlternateSetting failed: 
> Insufficient system resources exist to complete the requested 
> service.” I have looked into existing topics regarding this issue but 
> found none answered, at least related to USB. Usually, the issue 
> appears to be more observable on computers that are not often turned 
> off, but we have had the issue at least once on every computer using 
> Windows. 

What are the endpoints are in your alternate settings?  Usually, this 
error means that your alternate setting contains an isochronous or 
interrupt endpoint, and the reservation you asked for exceeded the 
reservation limit for the bus.  For example, if you try to start two 
video cameras on a USB 2 bus that's already running USB audio, that will 
exceed the limit.

-- 
Tim Roberts,ti...@pr...
Providenza & Boekelheide, Inc.