Hello, I'm currently working on a project that communicates with an FPGA board over a USB link. This board sends a heartbeat message to our PC every 8 seconds. Every once in a while this message is not processed by our software that is listening on the USB port until after 12 seconds expire. After putting an Elysis USB analyzer on the bus we were able to prove that the message does come over the wire at the proper 8 second interval. However, the URB call back is not invoked until 4 seconds later. I put some debug statements in the EHCI driver and below is the output of what I'm seeing. Basically these logs show that not even scan_async is invoking qh_completions until 4 seconds later. I put a new line in between each 8 second interval for easier readability. As shown, the last one prints 12 seconds later. The first line of each interval is printed right before scan_async calls qh_completions. The next two lines are printed inside of qh_completions once a QTD has been detected as deactivated. I'm just wondering if anyone can help me determine if this is a hardware problem with the host controller? I know there have been some updates to the ehci software on newer kernel releases but I suspect that this specific problem is not address by those changes and it is not a sw problem. The following is what I'm running: 2.6.34.8-0.2 Kernel from OpenSuse EHCI Chipset is an Intel 82801H (ICH8) //Message 1 on time Jun 14 21:06:39 magic kernel: [ 128.156346] TEMPMSGCHECK---Check invoked for our pipe at scan_async. Time is 4294142,643091 Jun 14 21:06:39 magic kernel: [ 128.156352] TEMPMSG---A serial QTD for endpoint 4 has completed 52 at 4294142,643091. Intresult is 32768 Jun 14 21:06:39 magic kernel: [ 128.156355] TEMPMSG---This serial QTD is a short packet. QH State is 1. Total QTDs are 1 //Message 2 on time Jun 14 21:06:47 magic kernel: [ 136.155976] TEMPMSGCHECK---Check invoked for our pipe at scan_async. Time is 4294150,640875 Jun 14 21:06:47 magic kernel: [ 136.155981] TEMPMSG---A serial QTD for endpoint 4 has completed 53 at 4294150,640875. Intresult is 32768 Jun 14 21:06:47 magic kernel: [ 136.155984] TEMPMSG---This serial QTD is a short packet. QH State is 1. Total QTDs are 1 //Message 3 on time Jun 14 21:06:55 magic kernel: [ 144.155479] TEMPMSGCHECK---Check invoked for our pipe at scan_async. Time is 4294158,639659 Jun 14 21:06:55 magic kernel: [ 144.155484] TEMPMSG---A serial QTD for endpoint 4 has completed 54 at 4294158,639659. Intresult is 32768 Jun 14 21:06:55 magic kernel: [ 144.155487] TEMPMSG---This serial QTD is a short packet. QH State is 1. Total QTDs are 1 //This message has come late (12 seconds instead of the usual 8 like the previous messages) USB Analyzer shows this message on the bus on time at 8 seconds Jun 14 21:07:07 magic kernel: [ 156.011433] TEMPMSGCHECK---Check invoked for our pipe at scan_async. Time is 4294170,493857 Jun 14 21:07:07 magic kernel: [ 156.011438] TEMPMSG---A serial QTD for endpoint 4 has completed 55 at 4294170,493857. Intresult is 32768 Jun 14 21:07:07 magic kernel: [ 156.011441] TEMPMSG---This serial QTD is a short packet. QH State is 1. Total QTDs are 1 Thank you, Daniel P Graves -- 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
