On Tue, Oct 19, 2010 at 9:03 AM, Xiaofan Chen <[email protected]> wrote: > On Tue, Oct 19, 2010 at 2:38 PM, Peter Stuge <[email protected]> wrote: >>> For the OpenOCD, we know there are some optimizations do be done on >>> the software to accelerate the USB JTAG cable. >> >> The bottleneck is stupid adapters.
I don't know that "stupid" is derogatory when we talk about hardware. KISS often does it... > People can actually get decent result from the so-called stupid > adapters. For examples, Urjtag project is now mainly using libusb-1.0 > and libftdi-1.0 instead of the old libusb-0.1 and libftdi-0.1x to get > much better result because of the async API support. Maybe > as the first step, OpenOCD can be modified to make use of the > async API provided by libusb-1.0 and libftdi-1.0. OpenOCD will create an entire read/write sequence before sending *anything* to the USB adapter. This would have been a bad thing if PC's were not infinitely fast. One interesting modification to OpenOCD might be to add some profiling metrics on inter-jtag_execute_queue() times. If there are large inter-jtag_execute_queue() times then I'd expect an async interface to help. OpenOCD already has a very nice mechanism to create long read/write chains, and it might have a lot of the potential benefit of an async API rolled into that optimization already. -- Øyvind Harboe US toll free 1-866-980-3434 / International +47 51 63 25 00 http://www.zylin.com/zy1000.html ARM7 ARM9 ARM11 XScale Cortex JTAG debugger and flash programmer _______________________________________________ Openocd-development mailing list [email protected] https://lists.berlios.de/mailman/listinfo/openocd-development
