ARM: 8634/1: hw_breakpoint: blacklist Scorpion CPUs

[pandora-kernel.git] / arch / arm / kernel / hw_breakpoint.c

diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index 2bc1a8e..bdafb83 100644 (file)
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -1001,6 +1001,22 @@ static int __init arch_hw_breakpoint_init(void)
                return 0;
        }
 
+       /*
+        * Scorpion CPUs (at least those in APQ8060) seem to set DBGPRSR.SPD
+        * whenever a WFI is issued, even if the core is not powered down, in
+        * violation of the architecture.  When DBGPRSR.SPD is set, accesses to
+        * breakpoint and watchpoint registers are treated as undefined, so
+        * this results in boot time and runtime failures when these are
+        * accessed and we unexpectedly take a trap.
+        *
+        * It's not clear if/how this can be worked around, so we blacklist
+        * Scorpion CPUs to avoid these issues.
+       */
+       if ((read_cpuid_id() & 0xff00fff0) == ARM_CPU_PART_SCORPION) {
+               pr_info("Scorpion CPU detected. Hardware breakpoints and watchpoints disabled\n");
+               return 0;
+       }
+
        /* Determine how many BRPs/WRPs are available. */
        core_num_brps = get_num_brps();
        core_num_wrps = get_num_wrps();