So, quick question to the collective linux-usb wisdom: when I collect a USB trace on my work-computer while running the command: dd if=/dev/zero of=/dev/sdX1 I see the same WRITE_10 commands of 122,880 bytes (240 sectors), but the glaring difference is that each such WRITE_10 command seems to be followed by ~ 27 READ_10 commands reading 1KB (2 sectors), whereas with the MAX3421 driver, I see consecutive WRITE_10 commands. Anybody know where those READ_10 commands are coming from? Is it a cheap way to poll the device if it's ready for the next block without having to use expensive OUT transactions that get NAK'd? I'll obviously investigate some more, but that's the first obvious difference I have noticed. --david On Tue, Mar 11, 2014 at 7:10 PM, David Mosberger <davidm@xxxxxxxxxx> wrote: > 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 -- 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
