On Tuesday 24 November 2015 12:15:13 Måns Rullgård wrote: > Arnd Bergmann <arnd@xxxxxxxx> writes: > > On Monday 23 November 2015 15:13:52 Stephen Boyd wrote: > >> On 11/23, Arnd Bergmann wrote: > >> > On Monday 23 November 2015 13:32:06 Stephen Boyd wrote: > >> > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig > >> > index b251013eef0a..bad6343c34d5 100644 > >> Do you have the information on these custom opcodes? I can work > >> that into the patches assuming the MIDR is different. > > > > Thomas Petazzoni said this in a private mail: > > > > | According to the datasheet, the PJ4B has integer signed and unsigned > > | divide, similar to the sdiv and udiv ARM instructions. But the way to > > | access it is by doing a MRC instruction. > > | > > | MRC<cond> p6, 1, Rd , CRn , CRm, 4 > > | > > |for PJ4B is the same as: > > | > > | SDIV Rd , Rn, Rm > > | > > | on ARM cores. > > | > > |And: > > | > > | MRC<cond> p6, 1, Rd , CRn , CRm, 0 > > | > > |for PJ4B is the same as: > > | > > | UDIV Rd , Rn, Rm > > | > > |on ARM cores. > > | > > |This is documented in the "Extended instructions" section of the > > |PJ4B datasheet. > > > > I assume what he meant was that this is true for both PJ4 and PJ4B > > but not for PJ4B-MP, which has the normal udiv/sdiv instructions. > > > > IOW, anything with CPU implementer 0x56 part 0x581 should use those, > > while part 0x584 can use the sdiv/udiv that it reports correctly. > > Or we could simply ignore those and they'd be no worse off than they are > now. Well, if we add all the infrastructure to do dynamic patching, we might as well use it here, that is a very little extra effort. I'm not convinced that the dynamic patching for idiv is actually needed but I'm not objecting either, and Stephen has done the work already. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
