> 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. Andrew -- 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
