On Tue, Oct 15, 2013 at 6:07 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > Why does the driver make this mistake? My initial assumption was wrong, the driver doesn't infrequently poll, but does so more often. I was misled by the confusing source. However, I now made usbmon traces and analyzed them with LibreOffice. During data transfer, the driver does a interrupt transfer about 48ms after the last one, and has to wait about 15ms for the result. But every 40 transfers, it executes 3 transfers without waiting inbetween and has to wait 63ms for the result. This is with transfer interval set to 10 on xhci. I also compiled the driver with transfer interval set to 1 (the original setting before my patch [1]), but the result is similar, an interrupt transfer every 44ms, and waiting of 19ms for the result. I don't have ehci hardware to test it. When the URB completition callback is executed, it calles complete(), while the driver is using wait_for_completion_interruptible_timeout() for this signal with 100ms timeout (originally that was 50ms but I changed it in patch [2] to make it work with xhci) This function seems to timeout on ehci hardware after about 700MB to 7GB transfered. I guess that the thread isn't scheduled fast enough under load, although the USB transfer was successful. > Does the device connect at high speed (480 Mb/s)? Yes, even with xhci it is only using 480Mb/s. > What needs to be fixed? It sounds like xhci-hcd and ehci-hcd are > working correctly and the problem is in the rts5139 driver. After looking at the usbmon traces, i have to agree. > bInterval = 10 means the polling period is 64 ms (for a high-speed > device). So a timeout of 100 ms should be adequate -- provided the > device always sends data over the interrupt endpoint without any > further delay. What i do not understand: with ehci hardware, the driver works when interval in the urb is set to 1 and the timeout is 50ms. With xhci, the urb appears to be scheduled not more often then every 64ms even if the interval in the urb is set to 1. I'm just looking for the correct solution for this issue. regards Marcus below some more info: [1] patch I made to get rid of syslog warnings because of wrong interval with xhci (that broke it for ehci hardware) https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6441a57887281106ed01222c2b0561ab25f77212 [2] patch I made to get it working on xhci (increasing timeout from 50 to 100): https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c5c141dfe737706d8bd57f40b4a9a8818c5ce4der T: Bus=03 Lev=01 Prnt=01 Port=02 Cnt=01 Dev#= 2 Spd=480 MxCh= 0 D: Ver= 2.00 Cls=ff(vend.) Sub=ff Prot=ff MxPS=64 #Cfgs= 1 P: Vendor=0bda ProdID=0129 Rev=39.60 S: Manufacturer=Generic S: Product=USB2.0-CRW S: SerialNumber=20100201396000000 C:* #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=500mA I:* If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=06 Prot=50 Driver=rts5139 E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=82(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=83(I) Atr=03(Int.) MxPS= 3 Ivl=64ms root@goetterdaemmerung:/home/marcus/linux# lsusb -v -s 3:2 Bus 003 Device 002: ID 0bda:0129 Realtek Semiconductor Corp. Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 255 Vendor Specific Class bDeviceSubClass 255 Vendor Specific Subclass bDeviceProtocol 255 Vendor Specific Protocol bMaxPacketSize0 64 idVendor 0x0bda Realtek Semiconductor Corp. idProduct 0x0129 bcdDevice 39.60 iManufacturer 1 Generic iProduct 2 USB2.0-CRW iSerial 3 20100201396000000 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 39 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 4 CARD READER bmAttributes 0xa0 (Bus Powered) Remote Wakeup MaxPower 500mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 3 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 6 bInterfaceProtocol 80 iInterface 5 Bulk-In, Bulk-Out, Interface Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x01 EP 1 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x83 EP 3 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0003 1x 3 bytes bInterval 10 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0000 (Bus Powered) root@goetterdaemmerung:/home/marcus/linux# -- 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
