On Mon, Dec 15, 2014 at 02:59:31PM +0530, Sanchayan Maity wrote: > Hello, > > On 12/15/2014 07:42 AM, Peter Chen wrote: > > 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 > > I had not checked the Vybrid errata. There are two erratas and I think one > of them might be relevant to the issue. > > e6857: Adding dTD to Primed Endpoint may not be recognized > The implementation of this errata (In fact, it should not be a errata, it is the software operation required which is applied to all chipidea controller) is already in the code. > It is interesting to see that it seems to be related to what you mention in the > third point. Honestly, not being much knowledgeable on the USB specifications > and protocol, I need to read up on what it exactly implies and I have got hold > of the USB 2.0 spec, but, some search on USB Prime Endpoint revealed on what > might be a similar issue here below. > https://community.freescale.com/thread/336166. The postpone freeing last dtd implementation has already been included in the current code. > > > - Seems your TX has some problems, any trace files using bus analyzer > > can confirm it? > > I would think so. I had already tried checking the USB and network packets with > Wireshark. After a few transactions, the USB packet carries a status of protocol > error with -71 and eventually the connection reset status -104 appears in the > USB packet. The network traces show TCP Dup Ack errors. I mean the trace file captured by hardware usb bus analyzer, but it doesn't matter if you don't have, it seems to relate with dtd list according your test. > > > - 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. > > This is quiet interesting. I just tried recompiling the kernel, as it is much > easier for me at the moment. The qmult value if not specified, takes on the > QMULT_DEFAULT value which is 5. I changed this to 1 and I notice no change with > the iperf tests. On a hunch, I changed DEFAULT_QLEN to 1, instead of 2 which is > for double buffering. Though this does not give me the 115Mbits/sec speed I would > have liked to see had it been working normally, the iperf tests ran reliably for three > hours, which was not the case before with even full speed not working for more than > an hour. This is probably not the solution, and seems to show me a full speed like > behaviour (though this would also be expected I guess without the double buffering) as > the average speeds are 11.6 Mbits/sec near a bit to the 8.67Mbits/sec for full speed > tests. I guess this is related to the dTD list problem as you mention and in the errata. > But, then that Frrescale thread gives the patch link below, which has been taken care of > it seems so I am not sure at all. So it can work reliable with single request for both tx/rx (QMULT_DEFAULT = 1 and DEFAULT_QLEN = 1), right? > > https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/patch/drivers/usb/chipidea/core.c?id=2e270412968d961ecde347343ffa67dfe39f6c95 This patch has already been in the kernel you are running. As far as I know, the Vybrid uses the same IP with i.mx6's, I will check it with my colleague. The next thing you can do maybe a little hard for you, you need to dump dtd and register like Richard at Freescale community suggested. -- 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
