Subject: Re: [PATCH v5 1/4] stmmac: create of compatible mdio bus for stmacc driver

From: Phil Reid <[email-masked]>
Date: Fri, 11 Dec 2015 09:44:52 +0800

G'day Giuseppe,

On 11/12/2015 1:16 AM, Giuseppe CAVALLARO wrote:
> Hi
>
> also pls fix this typo
>
> stmmac: create of compatible mdio bus for stmacc driver
>                                           ^^^^^^^^
>                                            stmmac
Will do.
>
> On 12/9/2015 9:39 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  | 31 +++++++++++++++-------
>>   .../net/ethernet/stmicro/stmmac/stmmac_platform.c  |  2 +-
>>   3 files changed, 31 insertions(+), 10 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..bb6f75c 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;
>> @@ -284,13 +304,6 @@ int stmmac_mdio_register(struct net_device *ndev)
>>           }
>>       }
>>
>> -    if (!found) {
>> -        pr_warn("%s: No PHY found\n", ndev->name);
>> -        mdiobus_unregister(new_bus);
>> -        mdiobus_free(new_bus);
>> -        return -ENODEV;
>> -    }
>
> hmm,  this could be necessary on some platforms that wants to
> get the phy addr at runtime and in case of failure then
> removes the registered bus.
>
Could make this conditional on (!found && !mdio_node).
Therefore if dt node exists it will be created regardless, otherwise unregister if nothing found.
Thoughts?

>> -
>>       priv->mii = new_bus;
>>
>>       return 0;
>> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
>> index d02691b..6863420 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");
>>ec
>> -    if (plat->phy_node || plat->phy_bus_name)
>
I think that would be dependent on the device tree.
However this may also work:
if ((plat->phy_node && !of_phy_is_fixed_link(np)) || plat->phy_bus_name)

> can this breaks some conf case?
>
>> +    if (plat->phy_bus_name)
>>           plat->mdio_bus_data = NULL;
>>       else
>>           plat->mdio_bus_data =
>>

Alternatively the solution would be to introduce some non standard device tree node
to force the creation of the mdio bus.

-- 
Regards
Phil Reid