linux-kernel - Re: [PATCH v7 14/26] PM / devfreq: rockchip-dfi: Prepare for multiple users

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Message-ID: <6eea0725-ac0b-0b45-4f6d-13799bc4bfb3@kernel.org>
Date:   Sat, 7 Oct 2023 03:46:02 +0900
From:   Chanwoo Choi <chanwoo@...nel.org>
To:     Sascha Hauer <s.hauer@...gutronix.de>,
        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>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: Re: [PATCH v7 14/26] PM / devfreq: rockchip-dfi: Prepare for multiple
 users

On 23. 7. 4. 18:32, Sascha Hauer wrote:
> When adding perf support later the DFI must be enabled when
> either of devfreq-event or perf is active. Prepare for that
> by adding a usage counter for the DFI. Also move enabling
> and disabling of the clock away from the devfreq-event specific
> functions to which the perf specific part won't have access.
> 
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> Reviewed-by: Sebastian Reichel <sebastian.reichel@...labora.com>
> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> ---
>  drivers/devfreq/event/rockchip-dfi.c | 57 +++++++++++++++++++---------
>  1 file changed, 40 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/devfreq/event/rockchip-dfi.c b/drivers/devfreq/event/rockchip-dfi.c
> index d39db5de7f19c..8a7af7c32ae0d 100644
> --- a/drivers/devfreq/event/rockchip-dfi.c
> +++ b/drivers/devfreq/event/rockchip-dfi.c
> @@ -68,13 +68,28 @@ struct rockchip_dfi {
>  	void __iomem *regs;
>  	struct regmap *regmap_pmu;
>  	struct clk *clk;
> +	int usecount;
> +	struct mutex mutex;
>  	u32 ddr_type;
>  	unsigned int channel_mask;
>  };
>  
> -static void rockchip_dfi_start_hardware_counter(struct rockchip_dfi *dfi)
> +static int rockchip_dfi_enable(struct rockchip_dfi *dfi)
>  {
>  	void __iomem *dfi_regs = dfi->regs;
> +	int ret = 0;
> +
> +	mutex_lock(&dfi->mutex);
> +
> +	dfi->usecount++;
> +	if (dfi->usecount > 1)
> +		goto out;
> +
> +	ret = clk_prepare_enable(dfi->clk);
> +	if (ret) {
> +		dev_err(&dfi->edev->dev, "failed to enable dfi clk: %d\n", ret);
> +		goto out;
> +	}
>  
>  	/* clear DDRMON_CTRL setting */
>  	writel_relaxed(HIWORD_UPDATE(0, DDRMON_CTRL_TIMER_CNT_EN | DDRMON_CTRL_SOFTWARE_EN |
> @@ -99,14 +114,30 @@ static void rockchip_dfi_start_hardware_counter(struct rockchip_dfi *dfi)
>  	/* enable count, use software mode */
>  	writel_relaxed(HIWORD_UPDATE(DDRMON_CTRL_SOFTWARE_EN, DDRMON_CTRL_SOFTWARE_EN),
>  		       dfi_regs + DDRMON_CTRL);
> +out:
> +	mutex_unlock(&dfi->mutex);
> +
> +	return ret;
>  }
>  
> -static void rockchip_dfi_stop_hardware_counter(struct rockchip_dfi *dfi)
> +static void rockchip_dfi_disable(struct rockchip_dfi *dfi)
>  {
>  	void __iomem *dfi_regs = dfi->regs;
>  
> +	mutex_lock(&dfi->mutex);
> +
> +	dfi->usecount--;
> +
> +	WARN_ON_ONCE(dfi->usecount < 0);
> +
> +	if (dfi->usecount > 0)
> +		goto out;
> +
>  	writel_relaxed(HIWORD_UPDATE(0, DDRMON_CTRL_SOFTWARE_EN),
>  		       dfi_regs + DDRMON_CTRL);
> +	clk_disable_unprepare(dfi->clk);
> +out:
> +	mutex_unlock(&dfi->mutex);
>  }
>  
>  static void rockchip_dfi_read_counters(struct rockchip_dfi *dfi, struct dmc_count *count)
> @@ -124,29 +155,20 @@ static void rockchip_dfi_read_counters(struct rockchip_dfi *dfi, struct dmc_coun
>  	}
>  }
>  
> -static int rockchip_dfi_disable(struct devfreq_event_dev *edev)
> +static int rockchip_dfi_event_disable(struct devfreq_event_dev *edev)
>  {
>  	struct rockchip_dfi *dfi = devfreq_event_get_drvdata(edev);
>  
> -	rockchip_dfi_stop_hardware_counter(dfi);
> -	clk_disable_unprepare(dfi->clk);
> +	rockchip_dfi_disable(dfi);
>  
>  	return 0;
>  }
>  
> -static int rockchip_dfi_enable(struct devfreq_event_dev *edev)
> +static int rockchip_dfi_event_enable(struct devfreq_event_dev *edev)
>  {
>  	struct rockchip_dfi *dfi = devfreq_event_get_drvdata(edev);
> -	int ret;
> -
> -	ret = clk_prepare_enable(dfi->clk);
> -	if (ret) {
> -		dev_err(&edev->dev, "failed to enable dfi clk: %d\n", ret);
> -		return ret;
> -	}
>  
> -	rockchip_dfi_start_hardware_counter(dfi);
> -	return 0;
> +	return rockchip_dfi_enable(dfi);
>  }
>  
>  static int rockchip_dfi_set_event(struct devfreq_event_dev *edev)
> @@ -190,8 +212,8 @@ static int rockchip_dfi_get_event(struct devfreq_event_dev *edev,
>  }
>  
>  static const struct devfreq_event_ops rockchip_dfi_ops = {
> -	.disable = rockchip_dfi_disable,
> -	.enable = rockchip_dfi_enable,
> +	.disable = rockchip_dfi_event_disable,
> +	.enable = rockchip_dfi_event_enable,
>  	.get_event = rockchip_dfi_get_event,
>  	.set_event = rockchip_dfi_set_event,
>  };
> @@ -272,6 +294,7 @@ static int rockchip_dfi_probe(struct platform_device *pdev)
>  		return PTR_ERR(dfi->regmap_pmu);
>  
>  	dfi->dev = dev;
> +	mutex_init(&dfi->mutex);
>  
>  	desc = &dfi->desc;
>  	desc->ops = &rockchip_dfi_ops;

Acked-by: Chanwoo Choi <cw00.choi@...sung.com>

-- 
Best Regards,
Samsung Electronics
Chanwoo Choi