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Date:   Mon, 21 Mar 2022 19:36:37 +0100
From:   Andrew Lunn <andrew@lunn.ch>
To:     Arun Ramadoss <arun.ramadoss@microchip.com>
Cc:     linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        Paolo Abeni <pabeni@redhat.com>,
        Jakub Kicinski <kuba@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        Russell King <linux@armlinux.org.uk>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        UNGLinuxDriver@microchip.com
Subject: Re: [RFC Patch net-next 3/3] net: phy: lan87xx: added ethtool SQI
 support
Message-ID: <YjjFtUEDm2Dta1ez@lunn.ch>
References: <20220321155337.16260-1-arun.ramadoss@microchip.com>
 <20220321155337.16260-4-arun.ramadoss@microchip.com>
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> +#define T1_DCQ_SQI_MSK			GENMASK(3, 1)

> +static int lan87xx_get_sqi(struct phy_device *phydev)
> +{
> +	u16 sqi_value[LAN87XX_SQI_ENTRY];

> +	for (i = 0; i < LAN87XX_SQI_ENTRY; i++) {
> +
> +		sqi_value[i] = FIELD_GET(T1_DCQ_SQI_MSK, rc);

> +
> +	/* Sorting SQI values */
> +	sort(sqi_value, LAN87XX_SQI_ENTRY, sizeof(u16), lan87xx_sqi_cmp, NULL);

Sort is quite heavyweight. Your SQI values are in the range 0-7 right?
So rather than have an array of LAN87XX_SQI_ENTRY entries, why not
create a histogram? You then just need to keep 8 uints. There is no
need to perform a sort to discard the outliers, simply remove from the
outer histogram buckets. And then you can calculate the average.

That should be faster and use less memory.

     Andrew