Re: [PATCH net 2/2] dpaa_eth: fix usage as DSA master, try 4

On Tue, 2020-06-16 at 18:12 +0300, Vladimir Oltean wrote:

On Tue, 16 Jun 2020 at 18:08, Vladimir Oltean [off-list ref] wrote:

quoted

On Tue, 16 Jun 2020 at 18:04, Joakim Tjernlund
[off-list ref] wrote:

quoted

On Tue, 2020-06-16 at 17:56 +0300, Vladimir Oltean wrote:

quoted

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Hi Joakim,

On Tue, 16 Jun 2020 at 17:51, Joakim Tjernlund
[off-list ref] wrote:

quoted

On Tue, 2020-06-16 at 17:41 +0300, Vladimir Oltean wrote:

quoted

From: Vladimir Oltean <vladimir.oltean@nxp.com>

The dpaa-eth driver probes on compatible string for the MAC node, and
the fman/mac.c driver allocates a dpaa-ethernet platform device that
triggers the probing of the dpaa-eth net device driver.

All of this is fine, but the problem is that the struct device of the
dpaa_eth net_device is 2 parents away from the MAC which can be
referenced via of_node. So of_find_net_device_by_node can't find it, and
DSA switches won't be able to probe on top of FMan ports.

It would be a bit silly to modify a core function
(of_find_net_device_by_node) to look for dev->parent->parent->of_node
just for one driver. We're just 1 step away from implementing full
recursion.

On T1040, the /sys/class/net/eth0 symlink currently points to:

../../devices/platform/ffe000000.soc/ffe400000.fman/ffe4e6000.ethernet/net/eth0

Just want to point out that on 4.19.x, the above patch still exists:
cd /sys
find -name eth0
./devices/platform/ffe000000.soc/ffe400000.fman/ffe4e6000.ethernet/net/eth0
./class/net/eth

By 'current' I mean 'the net tree just before this patch is applied',
i.e. a v5.7 tree with "dpaa_eth: fix usage as DSA master, try 3"
reverted.

Confused, with patch reverted(and DSA working) in 4.19, I have
  ../../devices/platform/ffe000000.soc/ffe400000.fman/ffe4e6000.ethernet/net/eth0
Is that the wanted path? Because I figured you wanted to change it to the path further down in this email?

 Jocke

Yes, this is the wanted path.
The path is fine for anything below commit 060ad66f9795 ("dpaa_eth:
change DMA device"), including your v4.19.y, that's the point. By
specifying that commit in the Fixes: tag, people who deal with
backporting to stable trees know to not backport it below that commit.
So your stable tree will only get the revert patch.

-Vladimir

Oh, sorry, now I see what you were saying. The paths are reversed in
the commit description. It should be:

Good:

../../devices/platform/ffe000000.soc/ffe400000.fman/ffe4e6000.ethernet/net/eth0

Bad:

../../devices/platform/ffe000000.soc/ffe400000.fman/ffe4e6000.ethernet/dpaa-ethernet.0/net/eth0

So I need to spin another version.

Thank you, I was doubting my(non native) understanding of English :)

 Jocke