On Wed, Mar 07, 2018 at 08:47:43AM +0100, Geert Uytterhoeven wrote: > Hi Inami-san, > > On Wed, Mar 7, 2018 at 2:48 AM, Gaku Inami <gaku.inami.xh@xxxxxxxxxxx> wrote: > >> From: geert.uytterhoeven@xxxxxxxxx [mailto:geert.uytterhoeven@xxxxxxxxx] On Behalf Of Geert Uytterhoeven > >> Sent: Monday, March 5, 2018 7:24 PM > > [snip] > >> > >> 411 for the A53 cores sounds a bit low to me, though. > >> Documentation/devicetree/bindings/arm/cpu-capacity.txt uses 578. > >> > >> Perhaps you already took into account the maximum clock frequencies? > >> According to the binding document, you should not do that (cfr. > >> "final capacities are 1024 for cluster0 and 446 for cluster1" in the > >> bindings doc). > > > > Thanks for your review. > > > > I set 411 for CA53 based on dhrystone measurement and current implementation. > > > > The average in 10 times of measurement as follows: > > > > cpu max-freq dhrystone > > --------------------------------- > > A57 1500 MHz 15532585 lps/s > > A53 1200 MHz 6241541 lps/s > > > > With the value of CA57 is scaled at 1024, I end up with 411 for CA53. > > However, since cpufreq is not available on renesas-devel-20180212-v4.16-rc1, > > the final capacity is set by directly using capacity-dmips-mhz in dt as below. > > Documentation/devicetree/bindings/arm/cpu-capacity.txt: > > "capacity-dmips-mhz is an optional cpu node [1] property: u32 value > representing CPU capacity expressed in normalized DMIPS/MHz. At boot time, the > maximum frequency available to the cpu is then used to calculate the capacity > value internally used by the kernel." > > IIUIC, you should thus not use 15532585 and 6241541 directly, but > scale them to the frequency. > > So the formula for CA53 becomes: > > 1024 / (15532585 / 1500) * (6241541 / 1200) = 514 > > > Considering cpufreq is available later, is it better to set the value(514) > > for CA53 scaled by different maximum frequencies? > > DT describes the hardware, not software limitations, so IMHO 514 is the correct > value. Yes agreed. Please refresh this patchset accordingly. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
