Subject: Re: [v6,1/4] stmmac: create of compatible mdio bus for stmmac driver

From: Gabriel Fernandez <[email-masked]>
Date: Wed, 17 Feb 2016 12:00:47 +0100

Hi all,

I work on STih410B2120 board and i have a regression since this patch 
(eth0: No PHY found)

My configuration is an Ethernet MAC with a "fixed link", and not 
connected to a normal MDIO-managed PHY device.

Please find my remark below.

On 12/14/2015 04:31 AM, Phil Reid wrote:
> The DSA driver needs to be passed a reference to an mdio bus. Typically
> the mac is configured to use a fixed link but the mdio bus still needs
> to be registered so that it con configure the switch.
> This patch follows the same process as the altera tse ethernet driver for
> creation of the mdio bus.
>
> Acked-by: Rob Herring <[email-masked]>
> Signed-off-by: Phil Reid <[email-masked]>
> ---
>   Documentation/devicetree/bindings/net/stmmac.txt   |  8 +++++++
>   drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c  | 26 +++++++++++++++++++---
>   .../net/ethernet/stmicro/stmmac/stmmac_platform.c  |  2 +-
>   3 files changed, 32 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/net/stmmac.txt b/Documentation/devicetree/bindings/net/stmmac.txt
> index f34fc3c..fd5ddf8 100644
> --- a/Documentation/devicetree/bindings/net/stmmac.txt
> +++ b/Documentation/devicetree/bindings/net/stmmac.txt
> @@ -47,6 +47,7 @@ Optional properties:
>   - snps,burst_len: The AXI burst lenth value of the AXI BUS MODE register.
>   - tx-fifo-depth: See ethernet.txt file in the same directory
>   - rx-fifo-depth: See ethernet.txt file in the same directory
> +- mdio: with compatible = "snps,dwmac-mdio", create and register mdio bus.
>   
>   Examples:
>   
> @@ -65,4 +66,11 @@ Examples:
>   		tx-fifo-depth = <16384>;
>   		clocks = <&clock>;
>   		clock-names = "stmmaceth";
> +		mdio0 {
> +			#address-cells = <1>;
> +			#size-cells = <0>;
> +			compatible = "snps,dwmac-mdio";
> +			phy1: ethernet-phy@0 {
> +			};
> +		};
>   	};
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
> index bba670c..16c85cc 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
> @@ -29,7 +29,7 @@
>   #include <linux/slab.h>
>   #include <linux/of.h>
>   #include <linux/of_gpio.h>
> -
> +#include <linux/of_mdio.h>
>   #include <asm/io.h>
>   
>   #include "stmmac.h"
> @@ -200,10 +200,29 @@ int stmmac_mdio_register(struct net_device *ndev)
>   	struct stmmac_priv *priv = netdev_priv(ndev);
>   	struct stmmac_mdio_bus_data *mdio_bus_data = priv->plat->mdio_bus_data;
>   	int addr, found;
> +	struct device_node *mdio_node = NULL;
> +	struct device_node *child_node = NULL;
>   
>   	if (!mdio_bus_data)
>   		return 0;
>   
> +	if (IS_ENABLED(CONFIG_OF)) {
> +		for_each_child_of_node(priv->device->of_node, child_node) {
> +			if (of_device_is_compatible(child_node,
> +						    "snps,dwmac-mdio")) {
> +				mdio_node = child_node;
> +				break;
> +			}
> +		}
> +
> +		if (mdio_node) {
> +			netdev_dbg(ndev, "FOUND MDIO subnode\n");
> +		} else {
> +			netdev_err(ndev, "NO MDIO subnode\n");
> +			return 0;
> +		}
> +	}
> +
>   	new_bus = mdiobus_alloc();
>   	if (new_bus == NULL)
>   		return -ENOMEM;
> @@ -231,7 +250,8 @@ int stmmac_mdio_register(struct net_device *ndev)
>   	new_bus->irq = irqlist;
>   	new_bus->phy_mask = mdio_bus_data->phy_mask;
>   	new_bus->parent = priv->device;
> -	err = mdiobus_register(new_bus);
> +
> +	err = of_mdiobus_register(new_bus, mdio_node);
>   	if (err != 0) {
>   		pr_err("%s: Cannot register as MDIO bus\n", new_bus->name);
>   		goto bus_register_fail;
> @@ -284,7 +304,7 @@ int stmmac_mdio_register(struct net_device *ndev)
>   		}
>   	}
>   
> -	if (!found) {
> +	if (!found && !mdio_node) {
>   		pr_warn("%s: No PHY found\n", ndev->name);
>   		mdiobus_unregister(new_bus);
>   		mdiobus_free(new_bus);
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> index d02691b..6a52fa1 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
> @@ -146,7 +146,7 @@ stmmac_probe_config_dt(struct platform_device *pdev, const char **mac)
>   	if (of_property_read_u32(np, "snps,phy-addr", &plat->phy_addr) == 0)
>   		dev_warn(&pdev->dev, "snps,phy-addr property is deprecated\n");
>   
> -	if (plat->phy_node || plat->phy_bus_name)
> +	if ((plat->phy_node && !of_phy_is_fixed_link(np)) || plat->phy_bus_name)
>   		plat->mdio_bus_data = NULL;
>   	else
>   		plat->mdio_bus_data =

It's impossible for me now to enter in the case "plat->mdio_bus_data = 
NULL;"

Due to the test of "&& !of_phy_is_fixed_link(np)", because i have a 
fixed_link.

And "plat->phy_bus_name" is always NULL (never affected...)

Maybe we should test mdio node here ? what is your opinion ?

Best Regards

Gabriel