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Subject: Re: [PATCH 2/3] drivers: devfreq: events: extend events by type of
 counted data
To:     Lukasz Luba <l.luba@partner.samsung.com>,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
Cc:     b.zolnierkie@samsung.com, krzk@kernel.org, robh+dt@kernel.org,
        mark.rutland@arm.com, kyungmin.park@samsung.com,
        m.szyprowski@samsung.com, s.nawrocki@samsung.com,
        myungjoo.ham@samsung.com, kgene@kernel.org
From:   Chanwoo Choi <cw00.choi@samsung.com>
Organization: Samsung Electronics
Message-ID: <628d298a-0c44-11c9-d27b-165cdfc0d2a2@samsung.com>
Date:   Wed, 17 Apr 2019 17:22:37 +0900
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Hi Lukasz,

On 19. 4. 17. 오후 4:48, Lukasz Luba wrote:
> This patch adds posibility to choose what type of data should be counted
> by the PPMU counter. Now the type comes from DT where the event has been
> defined. When there is no 'event-data-type' the default value is used,
> which is 'read data in bytes'.
> It is needed when you want to know not only read+write data bytes but
> i.e. only write data in byte, or number of read requests, etc.
> 
> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
> ---
>  drivers/devfreq/event/exynos-ppmu.c | 38 +++++++++++++++++++++++++------------
>  include/linux/devfreq-event.h       |  6 ++++++
>  2 files changed, 32 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/devfreq/event/exynos-ppmu.c b/drivers/devfreq/event/exynos-ppmu.c
> index c61de0b..e5f81a5 100644
> --- a/drivers/devfreq/event/exynos-ppmu.c
> +++ b/drivers/devfreq/event/exynos-ppmu.c
> @@ -140,6 +140,7 @@ static int exynos_ppmu_set_event(struct devfreq_event_dev *edev)
>  	int id = exynos_ppmu_find_ppmu_id(edev);
>  	int ret;
>  	u32 pmnc, cntens;
> +	u32 evt_sel = edev->desc->data_type;
>  
>  	if (id < 0)
>  		return id;
> @@ -154,9 +155,12 @@ static int exynos_ppmu_set_event(struct devfreq_event_dev *edev)
>  	if (ret < 0)
>  		return ret;
>  
> -	/* Set the event of Read/Write data count  */
> -	ret = regmap_write(info->regmap, PPMU_BEVTxSEL(id),
> -				PPMU_RO_DATA_CNT | PPMU_WO_DATA_CNT);
> +	/* Check if the data type has been defined in DT, use default if not */
> +	if (evt_sel == UINT_MAX)
> +		evt_sel = PPMU_RO_DATA_CNT | PPMU_WO_DATA_CNT;
> +
> +	/* Set the event of Read or Write or both (RDWR) data count  */
> +	ret = regmap_write(info->regmap, PPMU_BEVTxSEL(id), evt_sel);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -357,6 +361,7 @@ static int exynos_ppmu_v2_set_event(struct devfreq_event_dev *edev)
>  	unsigned int pmnc, cntens;
>  	int id = exynos_ppmu_find_ppmu_id(edev);
>  	int ret;
> +	u32 evt_sel = edev->desc->data_type;
>  
>  	/* Enable all counters */
>  	ret = regmap_read(info->regmap, PPMU_V2_CNTENS, &cntens);
> @@ -368,24 +373,28 @@ static int exynos_ppmu_v2_set_event(struct devfreq_event_dev *edev)
>  	if (ret < 0)
>  		return ret;
>  
> -	/* Set the event of Read/Write data count  */
> +
> +	/* Set the event of proper data type counting.
> +	 * Check if the data type has been defined in DT,
> +	 * use default if not.
> +	 */
>  	switch (id) {
>  	case PPMU_PMNCNT0:
>  	case PPMU_PMNCNT1:
>  	case PPMU_PMNCNT2:
> -		ret = regmap_write(info->regmap, PPMU_V2_CH_EVx_TYPE(id),
> -				PPMU_V2_RO_DATA_CNT | PPMU_V2_WO_DATA_CNT);
> -		if (ret < 0)
> -			return ret;
> +		if (evt_sel == UINT_MAX)
> +			evt_sel = PPMU_V2_RO_DATA_CNT | PPMU_V2_WO_DATA_CNT;
>  		break;
>  	case PPMU_PMNCNT3:
> -		ret = regmap_write(info->regmap, PPMU_V2_CH_EVx_TYPE(id),
> -				PPMU_V2_EVT3_RW_DATA_CNT);
> -		if (ret < 0)
> -			return ret;
> +		if (evt_sel == UINT_MAX)
> +			evt_sel = PPMU_V2_EVT3_RW_DATA_CNT;
>  		break;
>  	}
>  
> +	ret = regmap_write(info->regmap, PPMU_V2_CH_EVx_TYPE(id), evt_sel);
> +	if (ret < 0)
> +		return ret;
> +
>  	/* Reset cycle counter/performance counter and enable PPMU */
>  	ret = regmap_read(info->regmap, PPMU_V2_PMNC, &pmnc);
>  	if (ret < 0)
> @@ -508,6 +517,7 @@ static int of_get_devfreq_events(struct device_node *np,
>  	struct device *dev = info->dev;
>  	struct device_node *events_np, *node;
>  	int i, j, count;
> +	int ret;
>  
>  	events_np = of_get_child_by_name(np, "events");
>  	if (!events_np) {
> @@ -544,6 +554,10 @@ static int of_get_devfreq_events(struct device_node *np,
>  		desc[j].driver_data = info;
>  
>  		of_property_read_string(node, "event-name", &desc[j].name);
> +		ret = of_property_read_u32(node, "event-data-type",
> +					   &desc[j].data_type);
> +		if (!ret)
> +			desc[i].data_type = UINT_MAX;

I think that it is not proper to use 'UINT_MAX'.
If you want to use the default value, you can initialize
the 'desc[i].data_type' according to the device type or compatible name.

For all exynos SoC except for exynos5433,
	desc[i].data_type = PPMU_RO_DATA_CNT | PPMU_WO_DATA_CNT;

For exynos5433,
	desc[i].data_type = PPMU_V2_EVT3_RW_DATA_CNT;

>  
>  		j++;
>  	}
> diff --git a/include/linux/devfreq-event.h b/include/linux/devfreq-event.h
> index 4db00b0..cc160b1 100644
> --- a/include/linux/devfreq-event.h
> +++ b/include/linux/devfreq-event.h
> @@ -81,14 +81,20 @@ struct devfreq_event_ops {
>   * struct devfreq_event_desc - the descriptor of devfreq-event device
>   *
>   * @name	: the name of devfreq-event device.
> + * @data_type	: the data type which is going to be counted in the register.
>   * @driver_data	: the private data for devfreq-event driver.
>   * @ops		: the operation to control devfreq-event device.
>   *
>   * Each devfreq-event device is described with a this structure.
>   * This structure contains the various data for devfreq-event device.
> + * The data_type describes what is going to be counted in the register.
> + * It might choose to count e.g. read requests, write data in bytes, etc.
> + * The full supported list of types is present in specyfic header in:
> + * include/dt-bindings/pmu/.

Why did you make the path name as the 'pmu' instead of 'ppmu'?

It might have some confusion because 'pmu' has
the two meaning in linux kernel.
- PMU, Power Management Unit
- PMU, Performance Monitoring Unit

>   */
>  struct devfreq_event_desc {
>  	const char *name;
> +	u32 data_type;
>  	void *driver_data;
>  
>  	const struct devfreq_event_ops *ops;
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics