* Rob Herring <robherring2@xxxxxxxxx> [121114 16:56]: > On 11/14/2012 04:21 PM, Tony Lindgren wrote: > > * Rob Herring <robherring2@xxxxxxxxx> [121114 13:59]: > >> On 11/14/2012 02:32 PM, Tony Lindgren wrote: > >>> > >>> Checking for the bit already set should work in this case, I'll post > >>> a patch for that shortly. > >> > >> Can you actually read the state of the diagnostic register in non-secure > >> mode? If you can on the A9, is the same true on A8 or others? > > > > Looks like it can be read on at least TI omap 4430 which is A9. > > But it reads as zero, so the below patch is what I came up with. > > > > No idea if assuming that zero value for the diagnostic register > > is safe.. What's the default value of the diagnostic register supposed > > to be? > > RTFM. Oh, wait it's a super secret, undocumented register. We shouldn't > even be talking about it. WITFM? :) > It could vary by rev, but I see 0 for the reset value, so this would not > work if the bootloader did not do any setup of the diagnostic register. OK > One way to determine secure mode on the A9 would be seeing if you can > change the auxcr register. Something like this (untested): > > mrc p15, 0, r0, c1, c0, 1; Read ACTLR > eor r1, r0, #0x100 ; Modify alloc in 1 way > mcr p15, 0, r1, c1, c0, 1 > mrc p15, 0, r2, c1, c0, 1; Read ACTLR > mcr p15, 0, r0, c1, c0, 1 ; Restore original value > cmp r1, r2 > bne skip_errata > > > It would be good to do this test for all the errata rather than just > this one. I recall writes to the aux control registers producing an exception on secure A8 based omaps, but I'll give that a try when I have a chance. 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
