arm: perf: prevent unbind/bind via sysfs

Unbinding and rebinding the ARM PMU driver via sysfs leads to a
warning followed by more errors:
  WARNING: CPU: 0 PID: 217 at kernel/irq/chip.c:1034 irq_modify_status+0x150/0x16c
  ..
  genirq: Flags mismatch irq 19. 00010c04 (arm-pmu) vs. 00010c04 (arm-pmu)
  hw perfevents: unable to request IRQ19 for ARM PMU counters
  hw perfevents: /pmu: failed to register PMU devices!
  armv7-pmu: probe of pmu failed with error -16

The driver is clearly not designed to be removed. Disable bind/
unbind for this driver.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c
index 57f01e0..5a51167 100644 (file)
--- a/arch/arm/kernel/perf_event_v7.c
+++ b/arch/arm/kernel/perf_event_v7.c
@@ -2030,6 +2030,7 @@ static struct platform_driver armv7_pmu_driver = {
        .driver         = {
                .name   = "armv7-pmu",
                .of_match_table = armv7_pmu_of_device_ids,
+               .suppress_bind_attrs = true,
        },
        .probe          = armv7_pmu_device_probe,
 };