Re: [PATCH v2] net: macb: do not scan PHYs manually

Nicolas Ferre
2016-04-29T12:40:46Z

Le 29/04/2016 14:25, Josh Cartwright a écrit :
> On Thu, Apr 28, 2016 at 07:34:59PM -0500, Josh Cartwright wrote:
>> On Thu, Apr 28, 2016 at 11:23:15PM +0200, Andrew Lunn wrote:
>>> On Thu, Apr 28, 2016 at 04:03:57PM -0500, Josh Cartwright wrote:
>>>> On Thu, Apr 28, 2016 at 08:59:32PM +0200, Andrew Lunn wrote:
>>>>> On Thu, Apr 28, 2016 at 01:55:27PM -0500, Nathan Sullivan wrote:
>>>>>> On Thu, Apr 28, 2016 at 08:43:03PM +0200, Andrew Lunn wrote:
>>>>>>>> I agree that is a valid fix for AT91, however it won't solve our problem, since
>>>>>>>> we have no children on the second ethernet MAC in our devices' device trees. I'm
>>>>>>>> starting to feel like our second MAC shouldn't even really register the MDIO bus
>>>>>>>> since it isn't being used - maybe adding a DT property to not have a bus is a
>>>>>>>> better option?
>>>>>>>
>>>>>>> status = "disabled"
>>>>>>>
>>>>>>> would be the unusual way.
>>>>>>>
>>>>>>> Andrew
>>>>>>
>>>>>> Oh, sorry, I meant we use both MACs on Zynq, however the PHYs are on the MDIO
>>>>>> bus of the first MAC. So, the second MAC is used for ethernet but not for MDIO,
>>>>>> and so it does not have any PHYs under its DT node. It would be nice if there
>>>>>> were a way to tell macb not to bother with MDIO for the second MAC, since that's
>>>>>> handled by the first MAC.
>>>>>
>>>>> Yes, exactly, add support for status = "disabled" in the mdio node.
>>>>
>>>> Unfortunately, the 'macb' doesn't have a "mdio node", or alternatively:
>>>> the node representing the mdio bus is the same node which represents the
>>>> macb instance itself. Setting 'status = "disabled"' on this node will
>>>> just prevent the probing of the macb instance.
>>>
>>> :-(
>>>
>>> It is very common to have an mdio node within the MAC node, for example imx6sx-sdb.dtsi
>>
>> Okay, I think that makes sense. I think, then, perhaps the solution to
>> our problem is to:
>>
>> 1. Modify the macb driver to support an 'mdio' node. (And adjust the
>> binding document accordingly). If the node is found, it's used for
>> of_mdiobus_register() w/o any of the manual scan madness.
>> 2. For backwards compatibility, in the case where an 'mdio' node does
>> not exist, leave the existing behavior the way it is now
>> (of_mdiobus_register() followed by manual scan) [perhaps warn of
>> deprecation as well?]
>> 3. Update binding docs to reflect the above.
>>
>> In this way, for our usecase, the 'status = "disabled"' in the newly
>> created 'mdio' node isn't necessary. It's sufficient for the node to
>> exist and be empty.
>
> Here's a (only build tested) attempt at implementing a part of this. I
> macb_mii_init() was getting complicated enough that I lifted out two
> helper functions for the dt/no-dt case. Sweeping the in-tree
> devicetrees to update them to place phys under an 'mdio' node is still
> to be done.
>
> Josh
>
> diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
> index eec3200..d843bc9 100644
> --- a/drivers/net/ethernet/cadence/macb.c
> +++ b/drivers/net/ethernet/cadence/macb.c
> @@ -419,11 +419,62 @@ static int macb_mii_probe(struct net_device *dev)
> return 0;
> }
>
> +static int macb_mii_of_init(struct macb *bp, struct device_node *np)
> +{
> + struct device_node *mdio;
> + int err, i;
> +
> + mdio = of_get_child_by_name(np, "mdio");
> + if (mdio)
> + return of_mdiobus_register(bp->mii_bus, mdio);
> +
> + dev_warn(&bp->pdev->dev,
> + "using deprecated PHY probing mechanism. Please update device tree.");

Do we need to warn here?

Too bad I was not aware of that earlier, I even updated some of my DTs
recently with only a phy node without the "mdio" one as parents :-\

> + /* try dt phy registration */
> + err = of_mdiobus_register(bp->mii_bus, np);
> + if (err)
> + return err;
> +
> + /* fallback to standard phy registration if no phy were
> + * found during dt phy registration
> + */
> + if (!phy_find_first(bp->mii_bus)) {
> + for (i = 0; i < PHY_MAX_ADDR; i++) {
> + struct phy_device *phydev;
> +
> + phydev = mdiobus_scan(bp->mii_bus, i);
> + if (IS_ERR(phydev)) {
> + err = PTR_ERR(phydev);
> + break;
> + }
> + }
> +
> + if (err)
> + goto err_out_unregister_bus;
> + }
> +
> + return err;
> +
> +err_out_unregister_bus:
> + mdiobus_unregister(bp->mii_bus);
> + return err;
> +}
> +
> +static int macb_mii_pdata_init(struct macb *bp,
> + struct macb_platform_data *pdata)
> +{
> + if (pdata)
> + bp->mii_bus->phy_mask = pdata->phy_mask;
> +
> + return mdiobus_register(bp->mii_bus);
> +}
> +
> static int macb_mii_init(struct macb *bp)
> {
> struct macb_platform_data *pdata;
> struct device_node *np;
> - int err = -ENXIO, i;
> + int err = -ENXIO;
>
> /* Enable management port */
> macb_writel(bp, NCR, MACB_BIT(MPE));
> @@ -446,33 +497,10 @@ static int macb_mii_init(struct macb *bp)
> dev_set_drvdata(&bp->dev->dev, bp->mii_bus);
>
> np = bp->pdev->dev.of_node;
> - if (np) {
> - /* try dt phy registration */
> - err = of_mdiobus_register(bp->mii_bus, np);
> -
> - /* fallback to standard phy registration if no phy were
> - * found during dt phy registration
> - */
> - if (!err && !phy_find_first(bp->mii_bus)) {
> - for (i = 0; i < PHY_MAX_ADDR; i++) {
> - struct phy_device *phydev;
> -
> - phydev = mdiobus_scan(bp->mii_bus, i);
> - if (IS_ERR(phydev)) {
> - err = PTR_ERR(phydev);
> - break;
> - }
> - }
> -
> - if (err)
> - goto err_out_unregister_bus;
> - }
> - } else {
> - if (pdata)
> - bp->mii_bus->phy_mask = pdata->phy_mask;
> -
> - err = mdiobus_register(bp->mii_bus);
> - }
> + if (np)
> + err = macb_mii_of_init(bp, np);
> + else
> + err = macb_mii_pdata_init(bp, pdata);
>
> if (err)
> goto err_out_free_mdiobus;

I'm okay with this. Thanks for having taken the initiative to implement it.

Bye,
--
Nicolas Ferre