linux-kernel - Re: [PATCH] perf/arm-cmn: Set PMU device parent

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Message-ID: <20240410180403.00004cff@Huawei.com>
Date: Wed, 10 Apr 2024 18:04:03 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Robin Murphy <robin.murphy@....com>
CC: <will@...nel.org>, <mark.rutland@....com>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf/arm-cmn: Set PMU device parent

On Tue,  9 Apr 2024 18:15:17 +0100
Robin Murphy <robin.murphy@....com> wrote:

> Now that perf supports giving the PMU device a parent, we can use our
> platform device to make the relationship between CMN instances and PMU
> IDs trivially discoverable, from either nominal direction:
> 
> root@...zy-taxi:~# ls /sys/devices/platform/ARMHC600:00 | grep cmn
> arm_cmn_0
> root@...zy-taxi:~# realpath /sys/bus/event_source/devices/arm_cmn_0/..
> /sys/devices/platform/ARMHC600:00
> 
> Signed-off-by: Robin Murphy <robin.murphy@....com>
Nice.  I'd forgotten all about this :( 

https://lore.kernel.org/all/20230404134225.13408-1-Jonathan.Cameron@huawei.com/
still has a bunch of these + there were many I never looked into.

Guess I should respin that series though probably 50% at least still apply.

J


> ---
>  drivers/perf/arm-cmn.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
> index 7ef9c7e4836b..b2c607cf3ad7 100644
> --- a/drivers/perf/arm-cmn.c
> +++ b/drivers/perf/arm-cmn.c
> @@ -2482,6 +2482,7 @@ static int arm_cmn_probe(struct platform_device *pdev)
>  	cmn->cpu = cpumask_local_spread(0, dev_to_node(cmn->dev));
>  	cmn->pmu = (struct pmu) {
>  		.module = THIS_MODULE,
> +		.parent = cmn->dev,
>  		.attr_groups = arm_cmn_attr_groups,
>  		.capabilities = PERF_PMU_CAP_NO_EXCLUDE,
>  		.task_ctx_nr = perf_invalid_context,