On Fri, Jun 20, 2014 at 1:45 PM, Will Deacon <will.deacon@xxxxxxx> wrote: > On Thu, Jun 19, 2014 at 05:40:49PM +0100, Tomasz Figa wrote: >> On 19.06.2014 18:31, Doug Anderson wrote: >> >>> My personal vote would be to submit a patch to change "cycles_t" to >> >>> always be 32-bits. Given that 32-bits was fine for udelay() for ARM >> >>> that seems sane and simple. If someone later comes up with a super >> >>> compelling reason why we need 64-bit timers for udelay (really??) then >> >>> they can later add all the complexity needed. >> >> >> >> Yes, this could work. I'm not sure what else cycles_t is used for, though. >> > >> > True, it is a bit questionable to change this since it's a type that's >> > not obviously just for udelay(). Perhaps a better option would be to >> > make a new typedef for the result of read_current_timer(). ...or just >> > change it to return a u32? >> > >> >> Sounds good to me, but let's hear other opinions. I'm adding Will and >> Jonathan as they wrote the ARM delay timer code. > > I think cycles_t is only used for small interval calculations at the moment, > but I remember Ted mentioning something about using it (or something > similar) as a source of early entropy, in which case the more bits the > better. > Will, Thanks for the clarification that cycles_t is used for short intervals. So it is safe to return lower 32 bit counter for read_current_timer. Tomasz, Doug, As of now let me send a minimal implementation of this read delay timer to fix the broken udelay for exynos platforms so that it goes to upstream in rc releases. I will also prepare a fix for all raw_readl/writel in mct to relaxed version to make it consistent. > That said, I can't find any code in the tree to that effect. > > Will > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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