[PATCH v3 7/9] net: mvmdio: add xmdio xsmi support

On Mon, Jun 12, 2017 at 11:17:39AM +0100, Russell King - ARM Linux wrote:

On Mon, Jun 12, 2017 at 11:57:43AM +0200, Antoine Tenart wrote:

quoted

+static const struct orion_mdio_ops *orion_mdio_get_ops(struct orion_mdio_dev *dev,
+						       int regnum)
+{
+	if (dev->bus_type == BUS_TYPE_XSMI && (regnum & MII_ADDR_C45))
+		return &orion_mdio_xsmi_ops;
+	else if (dev->bus_type == BUS_TYPE_SMI)
+		return &orion_mdio_smi_ops;
+
+	return ERR_PTR(-EOPNOTSUPP);
+}

Oh, this is where you're doing it - I'm not sure having this complexity
is really necessary - there is no dynamic choice between the two.  This
seems to be way over-engineered.

You might as well make the SMI operations fail if MII_ADDR_C45 is set,
and the XSMI operations fail if MII_ADDR_C45 is not set.

Hmm, I think this whole driver is over-engineered:

1. the mdio read/write functions implement their own locking.

   At the MDIO level, there is already locking in the form of a per-bus
   lock "bus->mdio_lock" which will be taken whenever either of these
   functions is called.  So the driver's "dev->lock" is redundant.

2. with the redundant locking removed, orion_mdio_write() becomes a
   call to orion_mdio_wait_ready() followed by a call to dev->ops->write.
   It seems that orion_mdio_wait_ready() could be a library function
   shared between a SMI version of orion_mdio_write() and a XSMI version.

3. the same is really true of orion_mdio_read(), although that function
   is a little more complex in itself, the result would actually end up
   being simpler.

With those changes together, it elimates "struct orion_mdio_ops" entirely,
and I think makes the driver smaller, simpler, and cleaner.

I wasn't able to completely get rid of the ops structure, but I think
this is cleaner.  I haven't tested these two patches yet.

 drivers/net/ethernet/marvell/mvmdio.c | 276 +++++++++++++++-------------------
 1 file changed, 123 insertions(+), 153 deletions(-)

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.