Re: [PATCH v5 2/2] arm: perf: Add event descriptions

[Mark Rutland <mark.rutland@arm.com>]

On Thu, Oct 15, 2015 at 04:29:15PM +0100, Will Deacon wrote:
> On Thu, Oct 15, 2015 at 08:15:06AM -0700, Drew Richardson wrote:
> > On Thu, Oct 15, 2015 at 02:21:12PM +0100, Will Deacon wrote:
> > > On Tue, Oct 13, 2015 at 08:36:45AM -0700, Drew Richardson wrote:
> > > > Add additional information about the ARM architected hardware events
> > > > to make counters self describing. This makes the hardware PMUs easier
> > > > to use as perf list contains possible events instead of users having
> > > > to refer to documentation like the ARM TRMs.
> > > > 
> > > > Signed-off-by: Drew Richardson <drew.richardson@arm.com>
> > > > ---
> > > >  arch/arm/kernel/perf_event_v7.c | 121 ++++++++++++++++++++++++++++++++++++++++
> > > >  drivers/perf/arm_pmu.c          |   1 +
> > > >  2 files changed, 122 insertions(+)
> > > 
> > > [...]
> > > 
> > > > diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
> > > > index 2365a32a595e..e933d2dd71c0 100644
> > > > --- a/drivers/perf/arm_pmu.c
> > > > +++ b/drivers/perf/arm_pmu.c
> > > > @@ -548,6 +548,7 @@ static void armpmu_init(struct arm_pmu *armpmu)
> > > >  		.stop		= armpmu_stop,
> > > >  		.read		= armpmu_read,
> > > >  		.filter_match	= armpmu_filter_match,
> > > > +		.attr_groups	= armpmu->pmu.attr_groups,
> > > 
> > > I don't understand this hunk. What's it doing?
> > 
> > I'm not 100% clear either on what it's doing. But without this line
> > the attr_groups don't get passed on and I don't see them on my TC2. I
> > debugged the issue down to this but it may not be the proper way to
> > solve the problem.
> 
> Oh yuck, it's because we call armpmu_init after cpu_pmu_init and the former
> uses struct initialisation and ends up zeroing anything set previously.
> 
> We should probably tidy all this up:
> 
>   * Remove armpmu_register and call perf_pmu_register directly from
>     arm_pmu_device_probe instead
> 
>   * Call armpmu_init immediately prior to arm_cpu_init

Assuming you mean cpu_pmu_init, how about the below?

Thanks,
Mark.

---->8----
>From f8a99a406f3dd7a272a6dee4a551436fea851f38 Mon Sep 17 00:00:00 2001
From: Mark Rutland <mark.rutland@arm.com>
Date: Thu, 15 Oct 2015 16:32:17 +0100
Subject: [PATCH] drivers/perf: kill armpmu_register

Nothing outside of drivers/perf/arm_pmu.c should call armpmu_register
any more, so it no longer needs to be in include/linux/perf/arm_pmu.h.
Additionally, by folding it in to arm_pmu_device_probe we can allow
drivers to override struct pmu fields without getting blatted by the
armpmu code.

This patch folds armpmu_register into arm_pmu_device_probe. The logging
to the console is moved to after the PMU is successfully registered with
the core perf code.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Suggested-by: Will Deacon <will.deacon@arm.com>
Cc: Drew Richardson <drew.richardson@arm.com>
Cc: Pawel Moll <pawel.moll@arm.com>
---
 drivers/perf/arm_pmu.c       | 14 +++++---------
 include/linux/perf/arm_pmu.h |  2 --
 2 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index f346960..15463cb 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -583,14 +583,6 @@ static void armpmu_init(struct arm_pmu *armpmu)
 	};
 }
 
-int armpmu_register(struct arm_pmu *armpmu, int type)
-{
-	armpmu_init(armpmu);
-	pr_info("enabled with %s PMU driver, %d counters available\n",
-			armpmu->name, armpmu->num_events);
-	return perf_pmu_register(&armpmu->pmu, armpmu->name, type);
-}
-
 /* Set at runtime when we know what CPU type we are. */
 static struct arm_pmu *__oprofile_cpu_pmu;
 
@@ -934,14 +926,18 @@ int arm_pmu_device_probe(struct platform_device *pdev,
 		goto out_free;
 	}
 
+	armpmu_init(pmu);
 	ret = cpu_pmu_init(pmu);
 	if (ret)
 		goto out_free;
 
-	ret = armpmu_register(pmu, -1);
+	ret = perf_pmu_register(&pmu->pmu, pmu->name, -1);
 	if (ret)
 		goto out_destroy;
 
+	pr_info("enabled with %s PMU driver, %d counters available\n",
+			pmu->name, pmu->num_events);
+
 	return 0;
 
 out_destroy:
diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
index bfa673b..83b5e34 100644
--- a/include/linux/perf/arm_pmu.h
+++ b/include/linux/perf/arm_pmu.h
@@ -111,8 +111,6 @@ struct arm_pmu {
 
 #define to_arm_pmu(p) (container_of(p, struct arm_pmu, pmu))
 
-int armpmu_register(struct arm_pmu *armpmu, int type);
-
 u64 armpmu_event_update(struct perf_event *event);
 
 int armpmu_event_set_period(struct perf_event *event);
-- 
1.9.1