target/linux/ifxmips/patches-2.6.30/010-mips_clocksource_init_war.patch

   1 Index: linux-2.6.30.5/arch/mips/kernel/cevt-r4k.c
   2 ===================================================================
   3 --- linux-2.6.30.5.orig/arch/mips/kernel/cevt-r4k.c     2009-08-16 23:19:38.000000000 +0200
   4 +++ linux-2.6.30.5/arch/mips/kernel/cevt-r4k.c  2009-09-02 18:26:26.000000000 +0200
   5 @@ -21,6 +21,22 @@
   6
   7  #ifndef CONFIG_MIPS_MT_SMTC
   8
   9 +/*
  10 + * Compare interrupt can be routed and latched outside the core,
  11 + * so a single execution hazard barrier may not be enough to give
  12 + * it time to clear as seen in the Cause register.  4 time the
  13 + * pipeline depth seems reasonably conservative, and empirically
  14 + * works better in configurations with high CPU/bus clock ratios.
  15 + */
  16 +
  17 +#define compare_change_hazard() \
  18 +       do { \
  19 +               irq_disable_hazard(); \
  20 +               irq_disable_hazard(); \
  21 +               irq_disable_hazard(); \
  22 +               irq_disable_hazard(); \
  23 +       } while (0)
  24 +
  25  static int mips_next_event(unsigned long delta,
  26                             struct clock_event_device *evt)
  27  {
  28 @@ -30,6 +46,7 @@
  29         cnt = read_c0_count();
  30         cnt += delta;
  31         write_c0_compare(cnt);
  32 +       compare_change_hazard();
  33         res = ((int)(read_c0_count() - cnt) > 0) ? -ETIME : 0;
  34         return res;
  35  }