linux-kernel - Re: [PATCH v2 2/2] net: phy: motorcomm: Add pad drive strength cfg support

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Message-ID: <ba94f81c-3fc0-303c-f0f9-8fd0ab7d33fe@motor-comm.com>
Date:   Sat, 6 May 2023 09:29:28 +0800
From:   Frank Sae <Frank.Sae@...or-comm.com>
To:     Samin Guo <samin.guo@...rfivetech.com>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        netdev@...r.kernel.org, Peter Geis <pgwipeout@...il.com>
Cc:     "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>,
        Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Yanhong Wang <yanhong.wang@...rfivetech.com>
Subject: Re: [PATCH v2 2/2] net: phy: motorcomm: Add pad drive strength cfg
 support



On 2023/5/5 17:05, Samin Guo wrote:
> The motorcomm phy (YT8531) supports the ability to adjust the drive
> strength of the rx_clk/rx_data, and the default strength may not be
> suitable for all boards. So add configurable options to better match
> the boards.(e.g. StarFive VisionFive 2)
> 
> Signed-off-by: Samin Guo <samin.guo@...rfivetech.com>
> ---
>  drivers/net/phy/motorcomm.c | 46 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 46 insertions(+)
> 
> diff --git a/drivers/net/phy/motorcomm.c b/drivers/net/phy/motorcomm.c
> index 2fa5a90e073b..191650bb1454 100644
> --- a/drivers/net/phy/motorcomm.c
> +++ b/drivers/net/phy/motorcomm.c
> @@ -236,6 +236,7 @@
>   */
>  #define YTPHY_WCR_TYPE_PULSE			BIT(0)
>  
> +#define YTPHY_PAD_DRIVE_STRENGTH_REG		0xA010
>  #define YTPHY_SYNCE_CFG_REG			0xA012
>  #define YT8521_SCR_SYNCE_ENABLE			BIT(5)
>  /* 1b0 output 25m clock
> @@ -260,6 +261,14 @@
>  #define YT8531_SCR_CLK_SRC_REF_25M		4
>  #define YT8531_SCR_CLK_SRC_SSC_25M		5
>  
> +#define YT8531_RGMII_RXC_DS_DEFAULT		0x3
> +#define YT8531_RGMII_RXC_DS_MAX			0x7
> +#define YT8531_RGMII_RXC_DS			GENMASK(15, 13)
> +#define YT8531_RGMII_RXD_DS_DEFAULT		0x3
> +#define YT8531_RGMII_RXD_DS_MAX			0x7
> +#define YT8531_RGMII_RXD_DS_LOW			GENMASK(5, 4) /* Bit 1/0 of rxd_ds */
> +#define YT8531_RGMII_RXD_DS_HI			BIT(12) /* Bit 2 of rxd_ds */


YT8531_RGMII_xxx is bit define for YTPHY_PAD_DRIVE_STRENGTH_REG, so it is better to put it under the define of YTPHY_PAD_DRIVE_STRENGTH_REG.

YT8531_RGMII_xxx bit define as reverse order:
#define YTPHY_PAD_DRIVE_STRENGTH_REG		0xA010
#define YT8531_RGMII_RXC_DS			GENMASK(15, 13)
#define YT8531_RGMII_RXD_DS_HI			BIT(12) /* Bit 2 of rxd_ds */     <-------
#define YT8531_RGMII_RXD_DS_LOW			GENMASK(5, 4) /* Bit 1/0 of rxd_ds */
...

> +
>  /* Extended Register  end */
>  
>  #define YTPHY_DTS_OUTPUT_CLK_DIS		0
> @@ -1495,6 +1504,7 @@ static int yt8531_config_init(struct phy_device *phydev)
>  {
>  	struct device_node *node = phydev->mdio.dev.of_node;
>  	int ret;
> +	u32 ds, val;
>  
>  	ret = ytphy_rgmii_clk_delay_config_with_lock(phydev);
>  	if (ret < 0)
> @@ -1518,6 +1528,42 @@ static int yt8531_config_init(struct phy_device *phydev)
>  			return ret;
>  	}
>  
> +	ds = YT8531_RGMII_RXC_DS_DEFAULT;
> +	if (!of_property_read_u32(node, "motorcomm,rx-clk-driver-strength", &val)) {
> +		if (val > YT8531_RGMII_RXC_DS_MAX)
> +			return -EINVAL;
> +
> +		ds = val;
> +	}
> +
> +	ret = ytphy_modify_ext_with_lock(phydev,
> +					 YTPHY_PAD_DRIVE_STRENGTH_REG,
> +					 YT8531_RGMII_RXC_DS,
> +					 FIELD_PREP(YT8531_RGMII_RXC_DS, ds));
> +	if (ret < 0)
> +		return ret;
> +
> +	ds = FIELD_PREP(YT8531_RGMII_RXD_DS_LOW, YT8531_RGMII_RXD_DS_DEFAULT);
> +	if (!of_property_read_u32(node, "motorcomm,rx-data-driver-strength", &val)) {
> +		if (val > YT8531_RGMII_RXD_DS_MAX)
> +			return -EINVAL;
> +
> +		if (val > FIELD_MAX(YT8531_RGMII_RXD_DS_LOW)) {
> +			ds = val & FIELD_MAX(YT8531_RGMII_RXD_DS_LOW);
> +			ds = FIELD_PREP(YT8531_RGMII_RXD_DS_LOW, ds);
> +			ds |= YT8531_RGMII_RXD_DS_HI;
> +		} else {
> +			ds = FIELD_PREP(YT8531_RGMII_RXD_DS_LOW, val);
> +		}
> +	}
> +
> +	ret = ytphy_modify_ext_with_lock(phydev,
> +					 YTPHY_PAD_DRIVE_STRENGTH_REG,
> +					 YT8531_RGMII_RXD_DS_LOW | YT8531_RGMII_RXD_DS_HI,
> +					 ds);
> +	if (ret < 0)
> +		return ret;
> +
>  	return 0;
>  }
>