On Wed, Aug 26, 2020 at 06:54:59PM +0000, Mikolaj Kucharski wrote: > On Wed, Aug 26, 2020 at 06:45:28PM +0000, Mikolaj Kucharski wrote: ... > > > > Do you have any theory why first control request is returning > > wTotalLength=32 and second is returning wTotalLength=55? It also > > seem that bNumInterface has different value between the runs. > > I ran more `scanimage -L` commands in a row and wTotalLength=32 doesn't > occur any more. As I'm remote to the machine and the printer I don't see > it, but I imagine that printer/scanner goes to sleep after certain > amount of time of inactivity. > > Maybe it's related that first call wakes up the printer/scanner and > then wTotalLength=32. After that when printer/scanner is up all > wTotalLength=55. I can test it again during a day tomorrow with > hours of break in between of `scanimage -L` runs to see am I seeing > more of this behaviour. >
Ok, so I waited 15+ minutes between scanimage -L, as I suspect that would be enough time to get printer to sleep and yeah, I see again wTotalLength=32: # grep -F '/bsd' /var/log/messages | cut -b35- | head -n30 /bsd: USB_DEVICE_GET_FDESC wTotalLength free = 25 /bsd: USB_DEVICE_GET_FDESC wTotalLength free = 55 /bsd: USB_DEVICE_GET_FDESC wTotalLength free = 25 /bsd: USB_DEVICE_GET_FDESC wTotalLength free = 25 /bsd: USB_DEVICE_GET_FDESC wTotalLength free = 216 /bsd: 1: /bsd: bLength=9 /bsd: bDescriptorType=2 /bsd: wTotalLength=32 /bsd: bNumInterface=1 /bsd: bConfigurationValue=1 /bsd: iConfiguration=0 /bsd: bmAttributes=0xc0 /bsd: bMaxPower=1 /bsd: 2: /bsd: bLength=9 /bsd: bDescriptorType=2 /bsd: wTotalLength=55 /bsd: bNumInterface=2 /bsd: bConfigurationValue=1 /bsd: iConfiguration=0 /bsd: bmAttributes=0xc0 /bsd: bMaxPower=1 /bsd: USB_DEVICE_GET_FDESC wTotalLength free = 55 /bsd: USB_DEVICE_GET_FDESC wTotalLength free = 55 /bsd: USB_DEVICE_GET_FDESC wTotalLength free = 25 /bsd: USB_DEVICE_GET_FDESC wTotalLength free = 25 /bsd: USB_DEVICE_GET_FDESC wTotalLength free = 216 /bsd: USB_DEVICE_GET_FDESC wTotalLength free = 216 /bsd: USB_DEVICE_GET_FDESC wTotalLength free = 55 -- Regards, Mikolaj
