> From: Bin Liu [mailto:b-liu@xxxxxx] > Hi, > > On Thu, May 05, 2016 at 12:22:33PM +0000, Andrew Goodbody wrote: > > > From: Bin Liu [mailto:b-liu@xxxxxx] > > > Hi, > > > > > > On Wed, May 04, 2016 at 03:48:50PM +0000, Andrew Goodbody wrote: > > > > Hi, > > > > > > > > I have been investigating communication issues with iPads. When > > > > the system is busy it seems that the musb driver is silently > > > > dropping occasional packets. I have a usbmon trace that does not > > > > show the packet and I have a trace from a hardware USB analyser > > > > that does show the packet. So the device is correctly sending the > > > > packet, it is even being ACKed, but it is not passed up to the > > > > application. The packet is a bulk transfer packet of 20 bytes. Can > > > > anyone please give me pointers to where to go looking for the > > > > problem? The syslog shows nothing relevant. > > > > > > What is the part number on the am3352 chip? > > > > AM3352BZCZ100 > > > > > What kernel version do you use? > > > > 4.5.0 > > > > > Is musb cppi dma enabled? If so, does the problem still happen when > > > CPPI disabled? > > > > Yes. Yes. When testing with PIO I did get the message "Rx interrupt with no > errors or packet!". > > > > > First try to turn on dynamic debug log in musb_host.c to check if > > > musb receives the packet or not. > > > > > > Regards, > > > -Bin. > > > > I am having problems doing this. If I enable the whole file then I get > > lots of messages on the console about /dev/kmsg buffer overrun. There > > are more then 26 million packets in the hardware trace and I have not > > worked out how to correlate any of the possible message from dynamic > > debug with those packets even when I enable some of the dynamic debug > > lines. I can see a few messages about "DMA complete but packet still > > in FIFO, CSR 2103" and just the occasional "extra TX2 ready, csr 2100" > > when I enable some of the lines for dynamic debug. > > Well, this issue would not be easy to debug. Is this with your custom board? > If so, have you run EyeDiagram test to rule out signal integrity problem? Are > you able to reproduce it with any TI EVM, such as Beaglebone Black? If so, > please explain the detail of the test case, I could try to reproduce it on my > side. Yes this is on a custom board and yes we did EyeDiagram tests. Also the ACK from the controller is seen, so that should rule out signal integrity issues. I have just reproduced this on the Beaglebone Black using the latest TI SDK. Do you have access to 16 iPads with lightning connectors and do you have a Mac running 10.10.x? > > > > Andrew > > Regards, > -Bin. -- 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
