On Sat, Jan 22, 2011 at 2:03 PM, simon qian <simonqian.open...@gmail.com> wrote: > According to the feedback of my patch for SWD. I was busy fixing these > feedback these days. > I found that dap_to_jtag is not called. So it will be problem to operate > JTAG after operating SWD. > In my opinion, dap_to_jtag should be not be called in jtag_init, > because dap_to_jtag is defined ONLY in adiv5 specification. > But if I call dap_to_jtag in arm_adi_v5.c or adi_v5_jtag.c, it will fail > because jtag_id is read before calling dap_to_jtag. > So I think the initialization sequence should be from upper layer to lower > layer, which means initialize adiv5 and then initialize jtag.
Hello Simon! As stated on the ARM Infocenter [1]: -one mode of operation should be selected after target power up, and this mode should not be changed -jtag is the default working mode after power-up -swd-to-jtag and jtag-to-swd should not impact device after power up, because sequences are designed not to interfere with dap-specific operations Therefore I think we should test how select-jtag works on targets other than ARM. According to the documentation it should be transparent and ensure target is in JTAG mode. If there are no problems with non-ARM targets having this sequence applied at initialization, we should put this into jtag_init procedure..? On the other hand even ARM states that target should not be switched between SWD and JTAG modes multiple times with no powerdown/powerup... but if we have more than one target on the line, one is JTAG and one is SWD, then we could ensure working state for them. Best regards, Tomek [1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0316d/Chdhfbhc.html -- CeDeROM, SQ7MHZ, http://www.tomek.cedro.info _______________________________________________ Openocd-development mailing list Openocd-development@lists.berlios.de https://lists.berlios.de/mailman/listinfo/openocd-development
