Subject: Re: [PATCH 6/7 v2] fs_enet: Be an of_platform device when CONFIG_PPC_CPM_NEW_BINDING is set.

From: Scott Wood <[email-masked]>
Date: Tue, 21 Aug 2007 11:47:41 -0500

Vitaly Bordug wrote:
> On Fri, 17 Aug 2007 13:17:18 -0500
> Scott Wood wrote:
> 
> 
>>The existing OF glue code was crufty and broken.  Rather than fix it,
>>it will be removed, and the ethernet driver now talks to the device
>>tree directly.
>>
> 
> A bit short description, I'd rather expect some specific improvements list,
> that are now up and running using device tree. Or if it is just move to new
> infrastucture, let's state that, too.

Some of specific binding changes (there are too many to exhaustively 
list) are enumerated in the "new CPM binding" patch, which I'll send 
after Kumar's include/asm-ppc patch goes in (since it modifies one of 
those files).

>>+#ifdef CONFIG_PPC_CPM_NEW_BINDING
>>+static int __devinit find_phy(struct device_node *np,
>>+                              struct fs_platform_info *fpi)
>>+{
>>+	struct device_node *phynode, *mdionode;
>>+	struct resource res;
>>+	int ret = 0, len;
>>+
>>+	const u32 *data = of_get_property(np, "phy-handle", &len);
>>+	if (!data || len != 4)
>>+		return -EINVAL;
>>+
>>+	phynode = of_find_node_by_phandle(*data);
>>+	if (!phynode)
>>+		return -EINVAL;
>>+
>>+	mdionode = of_get_parent(phynode);
>>+	if (!phynode)
>>+		goto out_put_phy;
>>+
>>+	ret = of_address_to_resource(mdionode, 0, &res);
>>+	if (ret)
>>+		goto out_put_mdio;
>>+
>>+	data = of_get_property(phynode, "reg", &len);
>>+	if (!data || len != 4)
>>+		goto out_put_mdio;
>>+
>>+	snprintf(fpi->bus_id, 16, PHY_ID_FMT, res.start, *data);
>>+
>>+out_put_mdio:
>>+	of_node_put(mdionode);
>>+out_put_phy:
>>+	of_node_put(phynode);
>>+	return ret;
>>+}
> 
> And without phy node? 

It returns -EINVAL. :-)

>>+#ifdef CONFIG_FS_ENET_HAS_FEC
>>+#define IS_FEC(match) ((match)->data == &fs_fec_ops)
>>+#else
>>+#define IS_FEC(match) 0
>>+#endif
>>+
> 
> Since we're talking directly with device tree, why bother with CONFIG_ stuff? We are able to figure it out from dts..

We are figuring it out from the DTS (that's what match->data is).  I 
just didn't want boards without a FEC to have to build in support for it 
and waste memory.

>>+	fpi->rx_ring = 32;
>>+	fpi->tx_ring = 32;
>>+	fpi->rx_copybreak = 240;
>>+	fpi->use_napi = 0;
>>+	fpi->napi_weight = 17;
>>+
> 
> 
> move params over to  dts?

No.  These aren't attributes of the hardware, they're choices the driver 
makes about how much memory to use and how to interact with the rest of 
the kernel.

>>+	ret = find_phy(ofdev->node, fpi);
>>+	if (ret)
>>+		goto out_free_fpi;
>>+
> 
> so we're hosed without phy node.

How is that different from the old code, where you're hosed without 
fep->fpi->bus_id?

>>+static struct of_device_id fs_enet_match[] = {
>>+#ifdef CONFIG_FS_ENET_HAS_SCC
> 
> 
> same nagging. Are we able to get rid of Kconfig arcane defining which SoC currently plays the game for fs_enet?

No, it's still needed for mpc885ads to determine pin setup and 
conflicting device tree node removal (though that could go away if the 
device tree is changed to reflect the jumper settings).

It's also useful for excluding unwanted code.  I don't like using 
8xx/CPM2 as the decision point for that -- why should I build in 
mac-scc.c if I have no intention of using an SCC ethernet (either 
because my board doesn't have one, or because it's slow and conflicts 
with other devices)?

-Scott