[PATCH net v2 1/4] auxiliary: Support hexadecimal ids

[Sean Anderson]

On 7/17/25 12:21, Greg Kroah-Hartman wrote:
> On Thu, Jul 17, 2025 at 12:04:15PM -0400, Sean Anderson wrote:
>> On 7/17/25 11:59, Greg Kroah-Hartman wrote:
>> > On Thu, Jul 17, 2025 at 11:49:37AM -0400, Sean Anderson wrote:
>> >> On 7/16/25 01:09, Greg Kroah-Hartman wrote:
>> >> > On Tue, Jul 15, 2025 at 08:01:07PM -0400, Sean Anderson wrote:
>> >> >> Support creating auxiliary devices with the id included as part of the
>> >> >> name. This allows for hexadecimal ids, which may be more appropriate for
>> >> >> auxiliary devices created as children of memory-mapped devices. If an
>> >> >> auxiliary device's id is set to AUXILIARY_DEVID_NONE, the name must
>> >> >> be of the form "name.id".
>> >> >> 
>> >> >> With this patch, dmesg logs from an auxiliary device might look something
>> >> >> like
>> >> >> 
>> >> >> [    4.781268] xilinx_axienet 80200000.ethernet: autodetected 64-bit DMA range
>> >> >> [   21.889563] xilinx_emac.mac xilinx_emac.mac.80200000 net4: renamed from eth0
>> >> >> [   32.296965] xilinx_emac.mac xilinx_emac.mac.80200000 net4: PHY [axienet-80200000:05] driver [RTL8211F Gigabit Ethernet] (irq=70)
>> >> >> [   32.313456] xilinx_emac.mac xilinx_emac.mac.80200000 net4: configuring for inband/sgmii link mode
>> >> >> [   65.095419] xilinx_emac.mac xilinx_emac.mac.80200000 net4: Link is Up - 1Gbps/Full - flow control rx/tx
>> >> >> 
>> >> >> this is especially useful when compared to what might happen if there is
>> >> >> an error before userspace has the chance to assign a name to the netdev:
>> >> >> 
>> >> >> [    4.947215] xilinx_emac.mac xilinx_emac.mac.1 (unnamed net_device) (uninitialized): incorrect link mode  for in-band status
>> >> >> 
>> >> >> Signed-off-by: Sean Anderson <sean.anderson at linux.dev>
>> >> >> ---
>> >> >> 
>> >> >> Changes in v2:
>> >> >> - Add example log output to commit message
>> >> > 
>> >> > I rejected v1, why is this being sent again?
>> >> 
>> >> You asked for explanation, I provided it. I specifically pointed out why
>> >> I wanted to do things this way. But I got no response. So here in v2.
>> > 
>> > Again, I said, "do not do that, this is not how ids work in the driver
>> > model", and you tried to show lots of reasons why you wanted to do it
>> > this way despite me saying so.
>> > 
>> > So again, no, sorry, this isn't ok.  Don't attempt to encode information
>> > in a device id like you are trying to do here, that's not what a device
>> > id is for at all.  I need to go dig up my old patch that made all device
>> > ids random numbers just to see what foolish assumptions busses and
>> > userspace tools are making....
>> 
>> But it *is* how ids work in platform devices.
> 
> No one should ever use platform devices/bus as an excuse to do anything,
> it's "wrong" in so many ways, but needs to be because of special
> reasons.  No other bus should work like that, sorry.
> 
>> And because my auxiliary
>> devices are created by a platform device, it is guaranteed that the
>> platform device id is unique and that it will also be unique for
>> auxiliary devices. So there is no assumption here about the uniqueness
>> of any given id.
> 
> Then perhaps use the faux device api instead?

There's *another* pseudo bus? OK the reason why is that faux was added
four months ago and there is nothing under Documentation for it. So I
had no idea it existed. I will have a look, but perhaps you should write
up some documentation about why someone might want to use a "faux" bus
over the auxiliary bus or MFD.

--Sean