Subject: Re: [PATCH v2 2/2] phy dp83867: Make rgmii parameters optional

From: Dan Murphy <[email-masked]>
Date: Mon, 16 May 2016 15:27:49 -0500

On 05/16/2016 01:52 PM, Alexander Graf wrote:
> If you compile without OF_MDIO support in an RGMII configuration, we fail
> to configure the dp83867 phy today by writing garbage into its configuration
> registers.
>
> On the other hand if you do compile with OF_MDIO and the phy gets loaded via
> device tree, you have to have the properties set in the device tree, otherwise
> we fail to load the driver and don't even attach the generic phy driver to
> the interface anymore.
>
> To make things slightly more consistent, make the rgmii configuration properties
> optional and allow a user to omit them in their device tree.
>
> Signed-off-by: Alexander Graf <[email-masked]>
> ---
>  drivers/net/phy/dp83867.c | 31 ++++++++++++++++++++++++++++---
>  1 file changed, 28 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/phy/dp83867.c b/drivers/net/phy/dp83867.c
> index 94cc278..1b01680 100644
> --- a/drivers/net/phy/dp83867.c
> +++ b/drivers/net/phy/dp83867.c
> @@ -65,6 +65,7 @@ struct dp83867_private {
>  	int rx_id_delay;
>  	int tx_id_delay;
>  	int fifo_depth;
> +	int values_are_sane;
>  };
>  
>  static int dp83867_ack_interrupt(struct phy_device *phydev)
> @@ -113,15 +114,30 @@ static int dp83867_of_init(struct phy_device *phydev)
>  	ret = of_property_read_u32(of_node, "ti,rx-internal-delay",
>  				   &dp83867->rx_id_delay);
>  	if (ret)
> -		return ret;
> +		goto invalid_dt;
>  
>  	ret = of_property_read_u32(of_node, "ti,tx-internal-delay",
>  				   &dp83867->tx_id_delay);
>  	if (ret)
> -		return ret;
> +		goto invalid_dt;

Optional means you may or may not have the entries

I would prefer to wrap the DT reading with the interface type check.

if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID ||
phydev->interface == PHY_INTERFACE_MODE_RGMII_ID  )

 	ret = of_property_read_u32(of_node, "ti,tx-internal-delay",
 				   &dp83867->tx_id_delay);
	if (ret)

goto invalid_dt;

Otherwise this continues to mandate that you need to declare all the DT entries
when in fact you may only have to declare 1.

And if the other interfaces are declared then DT entries are ignored.  And configuring
internal delay is not required per section 8.9 footnote 3 of the data sheet.

Dan

>  
> -	return of_property_read_u32(of_node, "ti,fifo-depth",
> +	ret = of_property_read_u32(of_node, "ti,fifo-depth",
>  				   &dp83867->fifo_depth);
> +	if (ret)
> +		goto invalid_dt;
> +
> +	dp83867->values_are_sane = 1;
> +
> +	return 0;
> +
> +invalid_dt:
> +	phydev_err(phydev, "missing properties in device tree");
> +
> +	/*
> +	 * We can still run with a broken dt by not using any of the optional
> +	 * parameters, so just don't set dp83867->values_are_sane.
> +	 */
> +	return 0;
>  }
>  #else
>  static int dp83867_of_init(struct phy_device *phydev)
> @@ -150,6 +166,15 @@ static int dp83867_config_init(struct phy_device *phydev)
>  		dp83867 = (struct dp83867_private *)phydev->priv;
>  	}
>  
> +	/*
> +	 * With no or broken device tree, we don't have the values that we would
> +	 * want to configure the phy with. In that case, cross our fingers and
> +	 * assume that firmware did everything correctly for us or that we don't
> +	 * need them.
> +	 */
> +	if (!dp83867->values_are_sane)
> +		return 0;
> +
>  	if (phy_interface_is_rgmii(phydev)) {
>  		ret = phy_write(phydev, MII_DP83867_PHYCTRL,
>  			(dp83867->fifo_depth << DP83867_PHYCR_FIFO_DEPTH_SHIFT));

-- 
------------------
Dan Murphy