I couldn't figure out how to force UHCI onto an EHCI chip but I did find I had some old IOGEAR USB 1.1 "extenders" (USB-over-CAT5 cable) and with those, the device does switch into full-speed mode on my computer: [ 886.371122] usb 1-1.3.1.1.4.2: USB disconnect, device number 15 [ 950.960459] usb 1-1.2: new full-speed USB device number 16 using ehci-pci [ 951.055170] usb 1-1.2: not running at top speed; connect to a high speed hub [ 951.061791] usb 1-1.2: New USB device found, idVendor=058f, idProduct=6387 [ 951.061797] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [ 951.061802] usb 1-1.2: Product: Mass Storage [ 951.061805] usb 1-1.2: Manufacturer: Generic [ 951.061809] usb 1-1.2: SerialNumber: BCABB02D [ 951.062390] scsi5 : usb-storage 1-1.2:1.0 [ 952.060285] scsi 5:0:0:0: Direct-Access Generic Flash Disk 8.07 PQ: 0 ANSI: 4 [ 952.061585] sd 5:0:0:0: Attached scsi generic sg3 type 0 [ 952.064648] sd 5:0:0:0: [sdc] 1968128 512-byte logical blocks: (1.00 GB/961 MiB) [ 952.065793] sd 5:0:0:0: [sdc] Write Protect is off [ 952.065801] sd 5:0:0:0: [sdc] Mode Sense: 23 00 00 00 [ 952.067012] sd 5:0:0:0: [sdc] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA [ 952.076695] sdc: sdc1 [ 952.080629] sd 5:0:0:0: [sdc] Attached SCSI removable disk With this setup, I can write to the device just fine: dd if=/dev/zero of=/dev/sdc1 count=10000 10000+0 records in 10000+0 records out 5120000 bytes (5.1 MB) copied, 15.1192 s, 339 kB/s No infinite NAK issue. Still scratching my head... --david On Tue, Mar 11, 2014 at 1:00 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 11 Mar 2014, David Mosberger wrote: > >> > It looks like the host controller is behaving correctly, which means >> > the fault is in the device. Have you tried plugging this device into a >> > regular Linux PC and running the same test? >> >> Yup, works fine at least at least at hispeed. I suppose I should try >> the "enable UHCI only" trick to see if I can test the device at >> full-speed on my computer. > > Yes, definitely, so that you are testing under the same conditions. > > Alan Stern > -- eGauge Systems LLC, http://egauge.net/, 1.877-EGAUGE1, fax 720.545.9768 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
