On Thu, Jul 9, 2009 at 8:05 AM, Xiaofan Chen<xiaof...@gmail.com> wrote:
> 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.
>
So I tried this way and generated the following patch.
Index: src/jtag/jlink.c
===================================================================
--- src/jtag/jlink.c (revision 2503)
+++ src/jtag/jlink.c (working copy)
@@ -864,15 +864,6 @@
{
result->usb_handle = usb_open(dev);
- /*
- * Some j-link dongles experience
intermittent communication
issues at startup to varying degrees
- * depending on the host operating system.
Troubleshooting this
problem all the way back to libusb
- * revealed that without a usb reset, the
hardware can start in
an uncertain state causing a litany
- * of annoying problems. The next step
was added to the original
code to address this problem.
- */
-
- usb_reset(result->usb_handle);
-
/* usb_set_configuration required under win32 */
usb_set_configuration(result->usb_handle,
dev->config[0].bConfigurationValue);
usb_claim_interface(result->usb_handle, 0);
@@ -908,6 +899,8 @@
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);
}
It does help to reduce the initialization error under Ubuntu 9.04, but
not completely. So it does not work unfortunately.
--
Xiaofan http://mcuee.blogspot.com
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