linux-kernel - Re: [PATCH net-next v3 2/3] phy: mscc: Add support for RGMII delay configuration

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Message-ID: <ZFz1Bb8byoR1mQxH@corigine.com>
Date:   Thu, 11 May 2023 16:00:37 +0200
From:   Simon Horman <simon.horman@...igine.com>
To:     Harini Katakam <harini.katakam@....com>
Cc:     andrew@...n.ch, hkallweit1@...il.com, linux@...linux.org.uk,
        davem@...emloft.net, kuba@...nel.org, edumazet@...gle.com,
        pabeni@...hat.com, vladimir.oltean@....com,
        wsa+renesas@...g-engineering.com, mkl@...gutronix.de,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        harinikatakamlinux@...il.com, michal.simek@....com,
        radhey.shyam.pandey@....com
Subject: Re: [PATCH net-next v3 2/3] phy: mscc: Add support for RGMII delay
 configuration

On Thu, May 11, 2023 at 05:38:07PM +0530, Harini Katakam wrote:
> Add support for optional rx/tx-internal-delay-ps from devicetree.
> - When rx/tx-internal-delay-ps is/are specified, these take priority
> - When either is absent,
> 1) use 2ns for respective settings if rgmii-id/rxid/txid is/are present
> 2) use 0.2ns for respective settings if mode is rgmii
> 
> Signed-off-by: Harini Katakam <harini.katakam@....com>
> ---
> v3 - Patch split:
> - Use rx/tx-internal-delay-ps with phy_get_internal_delay
> - Change RGMII delay selection precedence
> - Update commit description and subject everywhere to say RGMII delays
> instead of RGMII tuning.
> 
>  drivers/net/phy/mscc/mscc.h      |  2 ++
>  drivers/net/phy/mscc/mscc_main.c | 35 +++++++++++++++++++++++++-------
>  2 files changed, 30 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/phy/mscc/mscc.h b/drivers/net/phy/mscc/mscc.h
> index 9acee8759105..ab6c0b7c2136 100644
> --- a/drivers/net/phy/mscc/mscc.h
> +++ b/drivers/net/phy/mscc/mscc.h
> @@ -374,6 +374,8 @@ struct vsc8531_private {
>  	 * package.
>  	 */
>  	unsigned int base_addr;
> +	u32 rx_delay;
> +	u32 tx_delay;

rx_delay and tx_delay are unsigned...

>  
>  #if IS_ENABLED(CONFIG_MACSEC)
>  	/* MACsec fields:
> diff --git a/drivers/net/phy/mscc/mscc_main.c b/drivers/net/phy/mscc/mscc_main.c
> index 91010524e03d..9e856231e464 100644
> --- a/drivers/net/phy/mscc/mscc_main.c
> +++ b/drivers/net/phy/mscc/mscc_main.c
> @@ -525,17 +525,14 @@ static int vsc85xx_rgmii_set_skews(struct phy_device *phydev, u32 rgmii_cntl,
>  {
>  	u16 rgmii_rx_delay_pos = ffs(rgmii_rx_delay_mask) - 1;
>  	u16 rgmii_tx_delay_pos = ffs(rgmii_tx_delay_mask) - 1;
> +	struct vsc8531_private *vsc8531 = phydev->priv;
>  	u16 reg_val = 0;
>  	int rc;
>  
>  	mutex_lock(&phydev->lock);
>  
> -	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID ||
> -	    phydev->interface == PHY_INTERFACE_MODE_RGMII_ID)
> -		reg_val |= RGMII_CLK_DELAY_2_0_NS << rgmii_rx_delay_pos;
> -	if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
> -	    phydev->interface == PHY_INTERFACE_MODE_RGMII_ID)
> -		reg_val |= RGMII_CLK_DELAY_2_0_NS << rgmii_tx_delay_pos;
> +	reg_val |= vsc8531->rx_delay << rgmii_rx_delay_pos;
> +	reg_val |= vsc8531->tx_delay << rgmii_tx_delay_pos;
>  
>  	rc = phy_modify_paged(phydev, MSCC_PHY_PAGE_EXTENDED_2,
>  			      rgmii_cntl,
> @@ -1808,10 +1805,34 @@ static irqreturn_t vsc8584_handle_interrupt(struct phy_device *phydev)
>  	return IRQ_HANDLED;
>  }
>  
> +static const int vsc8531_internal_delay[] = {200, 800, 1100, 1700, 2000, 2300,
> +					     2600, 3400};
>  static int vsc85xx_config_init(struct phy_device *phydev)
>  {
> -	int rc, i, phy_id;
> +	int delay_size = ARRAY_SIZE(vsc8531_internal_delay);
>  	struct vsc8531_private *vsc8531 = phydev->priv;
> +	struct device *dev = &phydev->mdio.dev;
> +	int rc, i, phy_id;
> +
> +	vsc8531->rx_delay = phy_get_internal_delay(phydev, dev, &vsc8531_internal_delay[0],
> +						   delay_size, true);

But phy_get_internal_delay a signed value.

> +	if (vsc8531->rx_delay < 0) {

This comparison can never be true due to the unsigned type of rx_delay.

> +		if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID ||
> +		    phydev->interface == PHY_INTERFACE_MODE_RGMII_ID)
> +			vsc8531->rx_delay = RGMII_CLK_DELAY_2_0_NS;
> +		else
> +			vsc8531->rx_delay = RGMII_CLK_DELAY_0_2_NS;
> +	}
> +
> +	vsc8531->tx_delay = phy_get_internal_delay(phydev, dev, &vsc8531_internal_delay[0],
> +						   delay_size, false);
> +	if (vsc8531->tx_delay < 0) {

Here too.

> +		if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
> +		    phydev->interface == PHY_INTERFACE_MODE_RGMII_ID)
> +			vsc8531->rx_delay = RGMII_CLK_DELAY_2_0_NS;
> +		else
> +			vsc8531->rx_delay = RGMII_CLK_DELAY_0_2_NS;
> +	}
>  
>  	rc = vsc85xx_default_config(phydev);
>  	if (rc)

---
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