Messages in this thread | | | Date | Tue, 28 Jun 2022 15:47:59 +0200 | From | Michael Walle <> | Subject | Re: fwnode_for_each_child_node() and OF backend discrepancy |
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[adding Horatiu Vultur, because we now digress to the bug in the switch, rather than that odd OF behavior]
Am 2022-06-28 15:29, schrieb Andy Shevchenko: > On Tue, Jun 28, 2022 at 3:23 PM Michael Walle <michael@walle.cc> wrote: >> >> >> I was trying to fix the lan966x driver [1] which doesn't work if there >> >> are disabled nodes in between. >> > >> > Can you elaborate what's wrong now in the behaviour of the driver? In >> > the code it uses twice the _available variant. >> >> Imagine the following device tree snippet: >> port0 { >> reg = <0>; >> status = "okay"; >> } >> port1 { >> reg = <1>; >> status = "disabled"; >> } >> port@2 { >> reg = <2>; >> status = "okay"; >> } >> >> The driver will set num_phys_ports to 2. When port@2 is probed, it >> will have the (correct!) physical port number 2. That will then >> trigger various EINVAL checks with "port_num >= num_phys_ports" or >> WARN()s. > > It means the above mentioned condition is wrong: it should be > > "port_idx >= num_phys_ports" (if the port_idx doesn't exists, that's > the bug in the first place)
I can't follow you here. Please note, that you need the actual physical port number. It's not a made up number, but corresponds to a physical port on that ethernet switch. So you can't just skip the disabled ones. port@2 must have port number 2.
>> So the easiest fix would be to actual count all the child nodes >> (regardless if they are available or not), assuming there are as >> many nodes as physical ports. >> >> But num_phys_ports being a property of the hardware > > So, name is wrong, that's how I read it, it should be > num_of_acrive_phys_ports (or alike).
See above, it is not just an iterator but corresponds to a hardware property.
>> I don't >> think it's good to deduce it by counting the child nodes anyway, > > Right. > >> but it should rather be a (hardcoded) property of the driver. > > Also good to update.
Horatiu, can we determine the actual number of ports (or maybe determine if its a LAN9668 or a LAN9662) from the hardware itself in an easy way? That way we wouldn't need a new compatible string, but could use the generic "lan966x" one.
-michael
[1] https://elixir.bootlin.com/linux/v5.19-rc4/source/drivers/net/ethernet/microchip/lan966x/lan966x_main.c
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