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

Josh Cartwright
2016-04-29T12:25:16Z

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.");
+
+ /* 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;