• Drew Fustini's avatar
    clocksource/drivers/timer-ti-dm: Fix regression from errata i940 fix · bceaae3b
    Drew Fustini authored
    The existing fix for errata i940 causes a conflict for IPU2 which is
    using timer 3 and 4. From arch/arm/boot/dts/dra7-ipu-dsp-common.dtsi:
    
      &ipu2 {
              mboxes = <&mailbox6 &mbox_ipu2_ipc3x>;
              ti,timers = <&timer3>;
              ti,watchdog-timers = <&timer4>, <&timer9>;
      };
    
    The conflict was noticed when booting mainline on the BeagleBoard X15
    which has a TI AM5728 SoC:
    
      remoteproc remoteproc1: 55020000.ipu is available
      remoteproc remoteproc1: powering up 55020000.ipu
      remoteproc remoteproc1: Booting fw image dra7-ipu2-fw.xem4
      omap-rproc 55020000.ipu: could not get timer platform device
      omap-rproc 55020000.ipu: omap_rproc_enable_timers failed: -19
      remoteproc remoteproc1: can't start rproc 55020000.ipu: -19
    
    This change modifies the errata fix to instead use timer 15 and 16 which
    resolves the timer conflict.
    
    It does not appear to introduce any latency regression. Results from
    cyclictest with original errata fix using dmtimer 3 and 4:
    
      # cyclictest --mlockall --smp --priority=80 --interval=200 --distance=0
      policy: fifo: loadavg: 0.02 0.03 0.05
    
      T: 0 ( 1449) P:80 I:200 C: 800368 Min:   0 Act:   32 Avg:   22 Max:  128
      T: 1 ( 1450) P:80 I:200 C: 800301 Min:   0 Act:   12 Avg:   23 Max:   70
    
    The results after the change to dmtimer 15 and 16:
    
      # cyclictest --mlockall --smp --priority=80 --interval=200 --distance=0
      policy: fifo: loadavg: 0.36 0.19 0.07
    
      T: 0 ( 1711) P:80 I:200 C: 759599 Min:   0 Act:    6 Avg:   22 Max:  108
      T: 1 ( 1712) P:80 I:200 C: 759539 Min:   0 Act:   19 Avg:   23 Max:   79
    
    Fixes: 25de4ce5 ("clocksource/drivers/timer-ti-dm: Handle dra7 timer wrap errata i940")
    Link: https://lore.kernel.org/linux-omap/YfWsG0p6to3IJuvE@x1/Suggested-by: default avatarSuman Anna <s-anna@ti.com>
    Reviewed-by: default avatarTony Lindgren <tony@atomide.com>
    Signed-off-by: default avatarDrew Fustini <dfustini@baylibre.com>
    Link: https://lore.kernel.org/r/20220204053503.1409162-1-dfustini@baylibre.comSigned-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
    bceaae3b
dra7-l4.dtsi 137 KB