linux-kernel - Re: [PATCH v5 16/25] PM / devfreq: rockchip-dfi: Add perf support

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Date:   Thu, 15 Jun 2023 15:13:16 +0200
From:   Sascha Hauer <s.hauer@...gutronix.de>
To:     linux-rockchip@...ts.infradead.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, Heiko Stuebner <heiko@...ech.de>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>, kernel@...gutronix.de,
        Michael Riesch <michael.riesch@...fvision.net>,
        Robin Murphy <robin.murphy@....com>,
        Vincent Legoll <vincent.legoll@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org,
        Sebastian Reichel <sebastian.reichel@...labora.com>
Subject: Re: [PATCH v5 16/25] PM / devfreq: rockchip-dfi: Add perf support

On Wed, May 24, 2023 at 10:31:44AM +0200, Sascha Hauer wrote:
> +static int rockchip_ddr_perf_event_add(struct perf_event *event, int flags)
> +{
> +	struct rockchip_dfi *dfi = container_of(event->pmu, struct rockchip_dfi, pmu);
> +
> +	dfi->active_events++;
> +
> +	if (dfi->active_events == 1)

We need to initialize dfi->last_perf_count here:

		rockchip_dfi_read_counters(dfi, &dfi->last_perf_count);

dfi->last_perf_count contains the start values for the counters and
without initializing this the u32 counter overflows are not correctly
handled.

Sascha


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