linux-kernel - Re: [PATCH v1 2/3] platform/mellanox: mlxbf-pmc: Add support for 64-bit counters and cycle count

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Message-ID: <e77f01b4-f314-6822-8533-95f37a42cd4f@linux.intel.com>
Date: Wed, 17 Apr 2024 16:18:37 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Shravan Kumar Ramani <shravankr@...dia.com>
cc: Hans de Goede <hdegoede@...hat.com>, Vadim Pasternak <vadimp@...dia.com>, 
    David Thompson <davthompson@...dia.com>, 
    platform-driver-x86@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 2/3] platform/mellanox: mlxbf-pmc: Add support for
 64-bit counters and cycle count

On Wed, 17 Apr 2024, Shravan Kumar Ramani wrote:

> Add support for programming any counter to monitor the cycle count.
> Since counting of cycles using 32-bit ocunters would result in frequent
> wraparounds, add the ability to combine 2 adjacent 32-bit counters to
> form 1 64-bit counter.
> Both these features are supported by BlueField-3 PMC hardware, hence
> the required bit-fields are exposed by the driver via sysfs to allow
> the user to configure as needed.
> 
> Signed-off-by: Shravan Kumar Ramani <shravankr@...dia.com>
> Reviewed-by: David Thompson <davthompson@...dia.com>
> Reviewed-by: Vadim Pasternak <vadimp@...dia.com>
> ---

> @@ -1799,6 +1902,37 @@ static int mlxbf_pmc_init_perftype_counter(struct device *dev, unsigned int blk_
>  		attr = NULL;
>  	}
>  
> +	if (pmc->block[blk_num].type == MLXBF_PMC_TYPE_CRSPACE) {
> +		/*
> +		 * Couple adjacent odd and even 32-bit counters to form 64-bit counters
> +		 * using "use_odd_counter" sysfs which has one bit per even counter.
> +		 */
> +		attr = &pmc->block[blk_num].attr_use_odd_counter;
> +		attr->dev_attr.attr.mode = 0644;
> +		attr->dev_attr.show = mlxbf_pmc_use_odd_counter_show;
> +		attr->dev_attr.store = mlxbf_pmc_use_odd_counter_store;
> +		attr->nr = blk_num;
> +		attr->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
> +							  "use_odd_counter");
> +		if (!attr->dev_attr.attr.name)
> +			return -ENOMEM;
> +		pmc->block[blk_num].block_attr[++i] = &attr->dev_attr.attr;
> +		attr = NULL;
> +
> +		/* Program crspace counters to count clock cycles using "count_clock" sysfs */
> +		attr = &pmc->block[blk_num].attr_count_clock;
> +		attr->dev_attr.attr.mode = 0644;
> +		attr->dev_attr.show = mlxbf_pmc_count_clock_show;
> +		attr->dev_attr.store = mlxbf_pmc_count_clock_store;
> +		attr->nr = blk_num;
> +		attr->dev_attr.attr.name = devm_kasprintf(dev, GFP_KERNEL,
> +							  "count_clock");
> +		if (!attr->dev_attr.attr.name)
> +			return -ENOMEM;
> +		pmc->block[blk_num].block_attr[++i] = &attr->dev_attr.attr;
> +		attr = NULL;
> +	}

Hi,

What was the reason why this driver could not use .dev_groups to setup 
sysfs (filtering can be done with .is_visible)?


-- 
 i.