On Fri, Dec 12, 2014 at 06:55:36PM +0530, Sanchayan Maity wrote: > Hello, > > On 12/12/2014 07:21 AM, Peter Chen wrote: > > On Thu, Dec 11, 2014 at 08:34:45AM -0600, Felipe Balbi wrote: > >> Hi, > >> > >> On Thu, Dec 11, 2014 at 04:08:43PM +0530, Sanchayan Maity wrote: > >>> Hello, > >>> > >>> I am working on a Freescale Cortex-A5 Vybrid Processor. The chip core > >>> is clocked at 500MHz and the USB IP core for this is by Chip-idea. I > >>> am running a 3.18-rc5 kernel on it and trying to use the USB gadget > >>> functionality. To be more specific the CDC ECM class. Currently, I > >>> cannot use this properly. If I use just "ping" to check, it works > >>> fine, but, after running iperf, even one transaction doesn't complete > >>> or completes rarely. Checking the CDC Ether interface with Wireshark > >>> shows, TCP Dup Ack messages and checking the USB bus with Wireshark, > >>> shows packets with USB Protocol Error -71 at one point and after that > >>> packets with USB connection Reset -104 error. If it's of any > >>> significance, I have Arch Linux with the 3.18 kernel running on my > >>> laptop with which the Vybrid connects. On the host side, the only > >>> error dmesg shows is "kevent 12 may have been dropped". I guess this > >>> is connected to the "TCP Previous Segment not captured" and "TCP Dup > >>> ACK" messages. > >>> > >>> My script for the gadget configuration is as below: > >>> > >>> /bin/mount none /mnt -t configfs > >>> /bin/mkdir /mnt/usb_gadget/g1 > >>> cd /mnt/usb_gadget/g1 > >>> /bin/mkdir configs/c.1 > >>> /bin/mkdir functions/ecm.0 > >>> /bin/mkdir strings/0x409 > >>> /bin/mkdir configs/c.1/strings/0x409 > >>> echo 0xa4a2 > idProduct > >>> echo 0x0525 > idVendor > >>> echo Freescale123 > strings/0x409/serialnumber > >>> echo Freescale > strings/0x409/manufacturer > >>> echo "USB Serial Gadget" > strings/0x409/product > >>> echo "Conf 1" > configs/c.1/strings/0x409/configuration > >>> echo 200 > configs/c.1/MaxPower > >>> ln -s functions/ecm.0 configs/c.1 > >>> echo ci_hdrc.0 > UDC > >>> /sbin/ifconfig usb0 up > >>> /sbin/ifconfig usb0 192.168.1.10 > >>> > >>> I have debug prints in the udc.c and u_ether.c using pr_debug and > >> > >> just a little hint, use any of the dev_*() macros next time, they'll > >> print the device name which helps figuring out which UDC you're using. > >> > >> Based on ci_hdrc.0 above, I suppose it's chipidea and Peter Chen > >> maintains that one, it really helps adding maintainers to Cc list. > >> > >>> enable them when required using dynamic debug. Without running iperf, > >>> using ping gives me a sequence of prints as below: > >>> > >>> [ 277.434409] In eth_start_xmit > >>> [ 277.434517] In UDC irq > >>> [ 277.434553] In usb_gadget_giveback_request > >>> [ 277.434567] In tx_complete > >>> [ 277.435443] In UDC irq > >>> [ 277.435477] In usb_gadget_giveback_request > >>> [ 277.435491] In rx_complete > >>> [ 277.435517] In rx_submit > >>> [ 277.435601] In eth_start_xmit > >>> [ 277.436441] In UDC irq > >>> [ 277.436465] In usb_gadget_giveback_request > >>> [ 277.436478] In rx_complete > >>> [ 277.436493] In rx_submit > >>> [ 277.436520] In usb_gadget_giveback_request > >>> [ 277.436533] In tx_complete > >>> [ 278.434865] In eth_start_xmit > >>> [ 278.434959] In UDC irq > >>> [ 278.434993] In usb_gadget_giveback_request > >>> [ 278.435006] In tx_complete > >>> [ 278.435881] In UDC irq > >>> [ 278.435910] In usb_gadget_giveback_request > >>> [ 278.435923] In rx_complete > >>> [ 278.435946] In rx_submit > >>> > >>> After running iperf without debug prints and then enabling before > >>> using ping gives me a sequence of prints as below > >>> [ 81.989827] In UDC irq > >>> [ 81.989871] In usb_gadget_giveback_request > >>> [ 81.989886] In rx_complete > >>> [ 81.989905] In rx_submit > >>> [ 82.989892] In UDC irq > >>> [ 82.989951] In usb_gadget_giveback_request > >>> [ 82.989967] In rx_complete > >>> [ 82.989992] In rx_submit > >>> [ 83.990064] In UDC irq > >>> [ 83.990126] In usb_gadget_giveback_request > >>> [ 83.990142] In rx_complete > >>> [ 83.990167] In rx_submit > >>> [ 84.990007] In UDC irq > >>> [ 84.990049] In usb_gadget_giveback_request > >>> [ 84.990064] In rx_complete > >>> [ 84.990083] In rx_submit > >>> [ 85.990085] In UDC irq > >>> [ 85.990147] In usb_gadget_giveback_request > >>> [ 85.990163] In rx_complete > >>> [ 85.990188] In rx_submit > >>> > >>> If I force a full speed configuration for this USB client port, I get > >>> a slightly more reliable operation where iperf can run for may be half > >>> an hour or so or almost an hour before it falls through. Putting in a > >>> delay of 100-150 microseconds in eth_start_xmit also improves it like > >>> full speed, but, still not reliable. If I run iperf with debug prints > >>> enable, this gives similar results to full speed config. After the > >>> failure of iperf test, even ping doesn't work. Bringing down this usb0 > >>> interface and then up again makes ping work again. I do realize that > >>> putting debug prints or delays like this is not the right thing to do, > >>> especially in ISR, but, just trying to debug. This is my first time > >>> digging in the USB stack. > >>> > >>> Based on the above, it seems there might a subtle bug or race > >>> condition somewhere in the execution call chain which I have not been > >>> able to trace yet. Can someone give me some pointers on how I can dig > >>> and debug further?. > >> > > > > I just tried latest usb-next with i.mx6 platform, it works ok with > > 10 mins iperf bi-direction test. > > We did think that it is probably an issue seen with Vybrids only. > - Check Vybrid errata to see if any missing in code - Seems your TX has some problems, any trace files using bus analyzer can confirm it? - Try to run g_ether: modprobe g_ether qmult=1, it will use only one request for transfer, to see if it is dtd list problem. -- Best Regards, Peter Chen -- 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
