On 7/8/09 5:05 PM, "Xiaofan Chen" <xiaof...@gmail.com> wrote:
> On Thu, Jul 9, 2009 at 5:53 AM, Gary Carlson<gcarl...@carlson-minot.com> > wrote: >> Zach/Spencer/Xiaofan, >> >> I did some more experimentation on the latest subversion (2499) and was able >> to tweak the jlink.c code slightly to possibly achieve three objectives: >> >> 1. Make jlink dongles work under Windows for Spencer. >> 2. Make jlink dongles work under Mac OS X for me. >> 3. Make jlink dongles work under Linux for Zach and Xiaofan. >> 4. Note the possible future problem that Xiaofan uncovered with libusb >> interactions in the Linux kernel and use it in such a way that the code in >> jlink.c won't cause future problems. >> >> I have confirmed #2 and believe that #4 is satisfied. What I don't know is >> whether #1 and #4 are. Could you try this out with your dongles and let me >> know what happens? >> >> If the patch works, I need to do a little cleanup but I didn't want to focus >> on that until I knew for sure whether it would solve the issues at hand. >> > > I will test this patch this evening. > > What I am thinking now is that this patch is still strange. Typically > the usb_set_configuration() will solve some problems for some USB > device (say USB toggle bit problems) since it is also a light weight > reset. > > But in case usb_reset() is necessary, it is typically called during the > closing stage. > > An example I wrote before. > http://www.microchip.com/forums/tm.aspx?m=340892 > > That is to say, typically you call these three instruction > when closing the usb_handle (after you finish the operation and > prepare for exit). > > usb_release_interface(devh, 0); > usb_rese(devh); //adding this line makes the program happy > usb_close(devh); > > > Which means in this case: > > static void jlink_usb_close(jlink_jtag_t *jlink_jtag) > { > usb_close(jlink_jtag->usb_handle); > free(jlink_jtag); > } > > becomes > > static void jlink_usb_close(jlink_jtag_t *jlink_jtag) > { > usb_release_interface((jlink_jtag->usb_handle,0); > usb_reset(jlink_jtag->usb_handle); > usb_close(jlink_jtag->usb_handle); > free(jlink_jtag); > } > > Could you try this? > > Personally I observed that normally first launch of OpenOCD is okay > and the subsequent launch of OpenOCD might cause startup problems. > So this indicates that the exit may not be so clean and this leads to > Jlink's initial status in a undesired state which even usb_set_configuration > can not help. > > But if you see the problems even during the first launch, then the above > may not help. > According the the libusb manual your use syntax is right. However, I get the feeling that the manual makes a deadly assumption that every software program that uses a USB port cleans it up properly at the end. I ran one experiment a few days ago alternating between a USB mouse and the J-link dongle and it caused a 100% startup failure rate in the J-link software. I am obviously assuming that cleanup is a problem, but I will make the concession that this is conjecture on my part without doing further research. I do agree with you though that if the intent is to follow the libusb manual we should do a reset at the end in the jlink code. If the test patch works for everyone, I can throw that in if everyone agrees. Gary Gary Carlson Gary Carlson, MSEE Principal Engineer Carlson-Minot Inc. _______________________________________________ Openocd-development mailing list Openocd-development@lists.berlios.de https://lists.berlios.de/mailman/listinfo/openocd-development
