Hi Will,
Will Deacon <will.deacon@xxxxxxx> writes:
> On Tue, Apr 03, 2012 at 11:01:53AM +0100, Shilimkar, Santosh wrote:
>> On Tue, Apr 3, 2012 at 3:17 PM, Will Deacon <will.deacon@xxxxxxx> wrote:
>> > It seems that they're both needed to get reliable PMU operation. Without the
>> > CLKDM_CAN_SWSUP fix, no interrupts are generated at all. Without the patch
>> > below ([1]), it seems that we don't generate enough. So it looks like we
>> > need them both.
>> >
>> I see. Can you please confirm if it is still the case with [1].
>
> Right, ignore my previous comment, I was using a vanilla 3.3 kernel without
> realising and therefore what I thought were PMU/CTI interrupts were actually
> just from a timer. Sorry for the confusion.
>
> So I've gone back to basics. Here is a branch containing what I believe
> should be all the patches required for the OMAP4 PMU:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git perf/omap4
>
> I've omitted the SWSUSP patch since you say it breaks pm, which is clearly not
> acceptable.
>
> The problem is, trying to boot this on my pandaboard results in a hang (see
> dmesg below). Even worse, the problem isn't easily bisectable since rebuilding
> a working image can give you something that no longer boots and I haven't found
> a reliable way to cause the lockup.
>
> I'll take JTAG for a whirl to see where we are. If anything looks wrong in
> my dmesg, please shout (there are plenty of things in there that look like
> they've gone awry).
Not sure why it hangs for you, but it worked for me both with your
branch on v3.3 and merging with v3.4-rc1[1]
Below is a Kconfig snippet[2] which I append to my .config after
building omap2plus_defconfig in order to build a perf/trace/PMU enabled
kernel for my Panda.
Kevin
[1]
# perf stat sleep 1
Performance counter stats for 'sleep 1':
9.582520 task-clock # 0.009 CPUs utilized
1 context-switches # 0.104 K/sec
0 CPU-migrations # 0.000 K/sec
147 page-faults # 0.015 M/sec
5096283 cycles # 0.532 GHz
607876 stalled-cycles-frontend # 11.93% frontend cycles idle
3285045 stalled-cycles-backend # 64.46% backend cycles idle
2722485 instructions # 0.53 insns per cycle
# 1.21 stalled cycles per insn
259247 branches # 27.054 M/sec
84274 branch-misses # 32.51% of all branches
1.015919088 seconds time elapsed
[2]
CONFIG_ARCH_OMAP2=n
CONFIG_ARCH_OMAP3=n # need to disable OMAP3 for CPU_HAS_PMU support, needed for perf on OMAP4
CONFIG_USB_EHCI_HCD=y
CONFIG_USB_NET_SMSC95XX=y
CONFIG_PROFILING=y
CONFIG_HW_PERF_EVENTS=y
CONFIG_PERF_EVENTS=y
CONFIG_PERF_COUNTERS=y
CONFIG_TRACEPOINTS=y
CONFIG_TRACING=y
CONFIG_GENERIC_TRACER=y
CONFIG_FTRACE=y
CONFIG_FUNCTION_TRACER=y
CONFIG_ENABLE_DEFAULT_TRACERS=y
CONFIG_STACK_TRACER=y
CONFIG_SCHED_TRACER=y
CONFIG_EVENT_POWER_TRACING_DEPRECATED=n
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