On Tue, 2020-06-16 at 17:41 +0300, Vladimir Oltean wrote:
> From: Vladimir Oltean <vladimir.olt...@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
>
> which pretty much illustrates the problem. The closest of_node we've got
> is the "fsl,fman-memac" at /soc@ffe000000/fman@400000/ethernet@e6000,
> which is what we'd like to be able to reference from DSA as host port.
>
> For of_find_net_device_by_node to find the eth0 port, we would need the
> parent of the eth0 net_device to not be the "dpaa-ethernet" platform
> device, but to point 1 level higher, aka the "fsl,fman-memac" node
> directly. The new sysfs path would look like this:
>
> ../../devices/platform/ffe000000.soc/ffe400000.fman/ffe4e6000.ethernet/dpaa-ethernet.0/net/eth0
>
> Actually this has worked before, through the SET_NETDEV_DEV mechanism,
> which sets the parent of the net_device as the parent of the platform
> device. But the device which was set as sysfs parent was inadvertently
> changed through commit 060ad66f9795 ("dpaa_eth: change DMA device"),
> which did not take into consideration the effect it would have upon
> of_find_net_device_by_node. So restore the old sysfs parent to make that
> work correctly.
>
> Fixes: 060ad66f9795 ("dpaa_eth: change DMA device")
> Signed-off-by: Vladimir Oltean <vladimir.olt...@nxp.com>
> ---
> drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> index c4416a5f8816..2972244e6eb0 100644
> --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> @@ -2914,7 +2914,7 @@ static int dpaa_eth_probe(struct platform_device *pdev)
> }
>
> /* Do this here, so we can be verbose early */
> - SET_NETDEV_DEV(net_dev, dev);
> + SET_NETDEV_DEV(net_dev, dev->parent);
> dev_set_drvdata(dev, net_dev);
>
> priv = netdev_priv(net_dev);
> --
> 2.25.1
>
