On Thu, Feb 26, 2015 at 5:14 AM, Matthijs van Duin <matthijsvanduin@xxxxxxxxx> wrote: > Thinking of it... unless the control module and relevant GPIO module > are connected to the same L4 interconnect (which they aren't in my > test case) I should actually perform at least a dummy read (aka "OCP > barrier") from the control module before accessing GPIO since > otherwise it's not even guaranteed that all writes to the control > module have completed. Joy. > > If you want guaranteed reliability, modify tck_pulse() to insert > aforementioned barrier + an actual delay at all three points where I > put comments about them. usleep(50) or so should do the job. Adding just the barrier works reliably for me, even at 1GHz. >> I guess I'll still connect TDO as it's not so much fun without it, >> going to try connecting to EMU0 too, hopefully it doesn't mess up the >> boot modes. > > Note that you can use *any* gpio. I just used one of the EMU pins > because the am335x lets you reconfigure those to GPIO and it was > conveniently nearby. Same here for me, this allowed to avoid adding a long wire which could interfere with case parts, etc. I've already performed the mod (just a solder bridge) and it works fine. On Thu, Feb 26, 2015 at 6:01 AM, Matthijs van Duin <matthijsvanduin@xxxxxxxxx> wrote: > On 26 February 2015 at 02:09, Grazvydas Ignotas <notasas@xxxxxxxxx> wrote: > >> Anyway I'm attaching my code too > > Ah, if this works then apparently the omap3 control module doesn't > check privilege. Yeah, even OMAP5 doesn't do it for me. > BTW, is this comment in hw-omap3.h true? > >> 0x23'002100, // assert cortex-a8 DBGEN > > My impression was that bit 13 of DAP's tap control register either > does nothing or at most enables the DAPCTL registers to be written, > but that setting bit 13 of the DAP_PC_FER register would still be > needed to assert DBGEN. Yes you're right, I've cleared bit 13 and everything works same way as before, and in all cases additional ap_write() is needed to actually set DBGEN. > > Also, > >> // address of cortex-a8 debug regs on debug APB >> constexpr u32 a8_debug = 0x54011'000; > > If bit 31 isn't set, then these writes should (afaik) be equivalent to > just performing them directly through the interconnect instead of > using JTAG. I don't know about that... To enable DBGEN, I just do: ap_write( 0x5401d030, 0x00002000 ); and it works. Using 0xd401d030 seems to work too. Thanks again, Gražvydas -- 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
