* Grazvydas Ignotas <notasas@xxxxxxxxx> [150215 13:34]: > Hi, > > Does anyone know if there is a way to make DBGEN signal high on > OMAP3530 and/or DM3730 without using a hardware debugger? My goal is > to make use of hardware watchpoints in Cortex-A8, but that requires > DBGEN to be high. > > The TRM states: > "The DBGEM signal on the Cortex-A8 is driven by setting bit 13 at > address 0x5401 D030 in the DAP-APB address space." > However regardless of how hard I try the writes to that register seem > to be ignored. I even tried to do it from IVA/C64x with no success. > (I assume DBGEM is a typo since Cortex-A8 manuals have no mention of > it, and they meant DBGEN there). > > It seems others had this problem too, and TI is as helpful as ever: > http://e2e.ti.com/support/dsp/omap_applications_processors/f/447/p/30011/104527 > > DBGEN is mentioned by Will Deacon's commit > 8954bb0da99b76c7ce5edf2f314807cff68b6ea8 , but I guess he mixed NIDEN > with DBGEN there (DBGAUTHSTATUS returns 0x000000ae so NIDEN is indeed > set here, and I have tried old kernel where OMAP3_EMU was still > available). Does the perf counter still work OK? Looks like OMAP3_EMU got removed by commit 184901a06a36 ("ARM: removing support for etb/etm in "arch/arm/kernel/""). The perf counter on omap3 used to work, but is buggy at least on 3430 because it eventually stops producing interrupts because of some bug in the Cortex-A8 version being used. Looking at the commits it seems that it probably only works for device tree based booting nowadays. Also, it seems that having the etm@54010000, etb@540000000 and etb@5401b000 entries only in the omap3-beagle*.dts files is wrong. To me it seems they should be in the omap3.dtsi and omap36xx.dtsi instead. Looks like those got added by commit 9d31620268a7 ("coresight: adding support for beagle and beagleXM"). So maybe moving the etb and etm entries to omap3.dtsi and omap36xx.dtsi is all you need with the current mainline kernel? > 0x5401D030 is referenced by some OpenOCD scripts, so I guess it's > writeable over jtag, but not by the CPU(s). It's quite a mysterious > otherwise undocumented register, I've noticed it's bit21 is some > status bit related to Cortex-A8's low power states. Have you checked the Cortex-A8 documentation for the debugger? It seems that's where they should be documented. Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
