• Gaku Inami's avatar
    arm64: dts: renesas: Add CPU capacity-dmips-mhz · 2250d856
    Gaku Inami authored
    Set the capacity-dmips-mhz for R-Car Gen3 SoCs, that is based on
    dhrystone. The average in 10 times of dhrystone result as follows:
    
    r8a7795 SoC (A57x4 + A53x4)
      CPU   max-freq   dhrystone
      ---------------------------------
      A57   1500 MHz  11470943 lps/s
      A53   1200 MHz   4798583 lps/s
    
    r8a7796 SoC (A57x2 + A53x4)
      CPU   max-freq   dhrystone
      ---------------------------------
      A57   1500 MHz  11463526 lps/s
      A53   1200 MHz   4793276 lps/s
    
    Based on above, capacity-dmips-mhz values are calculated as follows:
    
    r8a7795 SoC
      A57 : 1024 / (11470943 / 1500) * (11470943 / 1500) = 1024
      A53 : 1024 / (11470943 / 1500) * ( 4798583 / 1200) =  535
    
    r8a7796 SoC
      A57 : 1024 / (11463526 / 1500) * (11463526 / 1500) = 1024
      A53 : 1024 / (11463526 / 1500) * ( 4793276 / 1200) =  535
    
    However, since each CPUs have different max frequencies, the final
    CPU capacities of A53 are scaled by this difference, the values are
    as follows.
    
    [r8a7795 SoC]
      $ cat /sys/devices/system/cpu/cpu*/cpu_capacity
      1024	<---- CPU capacity of A57
      1024
      1024
      1024
      428	<---- CPU capacity of A53
      428
      428
      428
    
    [r8a7796 SoC]
      $ cat /sys/devices/system/cpu/cpu*/cpu_capacity
      1024	<---- CPU capacity of A57
      1024
      428	<---- CPU capacity of A53
      428
      428
      428
    Signed-off-by: default avatarGaku Inami <gaku.inami.xh@renesas.com>
    Reviewed-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
    Signed-off-by: default avatarSimon Horman <horms+renesas@verge.net.au>
    2250d856
r8a7795.dtsi 85.7 KB