netdev - Re: [net-next PATCH v2 2/3] net: mdio: ipq4019: add support for clock-frequency property

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Date: Sun, 4 Feb 2024 17:59:10 +0800
From: Jie Luo <quic_luoj@...cinc.com>
To: Christian Marangi <ansuelsmth@...il.com>, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio
	<konrad.dybcio@...aro.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric
 Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni
	<pabeni@...hat.com>, Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>, Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell
 King <linux@...linux.org.uk>,
        Robert Marko <robert.marko@...tura.hr>,
        <linux-arm-msm@...r.kernel.org>, <netdev@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [net-next PATCH v2 2/3] net: mdio: ipq4019: add support for
 clock-frequency property



On 1/30/2024 8:35 AM, Christian Marangi wrote:
> +
> +	/* If div is /256 assume nobody have set this value and
> +	 * try to find one MDC rate that is close the 802.3 spec of
> +	 * 2.5MHz
> +	 */
> +	for (div = 256; div >= 8; div /= 2) {
> +		/* Stop as soon as we found a divider that
> +		 * reached the closest value to 2.5MHz
> +		 */
> +		if (DIV_ROUND_UP(ahb_rate, div) > 2500000)
> +			break;

Hi Christian,
Sorry for the delayed review.

The MDIO hardware block supports higher frequency 6.25M and 12.5M,
Would you remove this 2.5MHZ limitation? On the IPQ platform, we
normally use 6.25MHZ.
> +
> +		priv->mdc_rate = DIV_ROUND_UP(ahb_rate, div);
> +	}
>   }