Re: [PATCH net-next v6 1/9] net: dsa: microchip: Add support for KSZ8463 global irq

[Bastien Curutchet <bastien.curutchet@bootlin.com>]

On 3/11/26 2:56 PM, Vladimir Oltean wrote:
> On Wed, Mar 11, 2026 at 01:53:38PM +0100, Bastien Curutchet wrote:
>> On 3/11/26 12:53 PM, Vladimir Oltean wrote:
>>> On Wed, Mar 11, 2026 at 11:02:35AM +0100, Bastien Curutchet wrote:
>>>> I, more or less, managed to fit this PTP support in the current framework,
>>>> but the next series I prepared to add periodic output support is full of
>>>> is_ksz8463() branches. So I think that I'll go with what you suggested and
>>>> try to move the KSZ8463 support in the ksz8995.c driver. It will probably be
>>>> cleaner this way.
>>>>
>>>> TBH I'm a bit lost with all these KSZ variants but IIUC KSZ8463 and KSZ8995
>>>> both belong to the 'old generation' of the hardware. Maybe a good split
>>>> would be to have these old switches in the ksz8995.c driver and keep the
>>>> rest under ksz_common infra.
>>>
>>> Wait, to make sure I understand, you said you're going to rebase this
>>> series onto the ksz8995 driver?
>>
>> Well I'll first add basic support for the KSZ8463 in the ksz8995 driver and
>> then add interrupt and PTP support on top of it yes. Did I misunderstand
>> you're suggestion ?
> 
> If we're splitting drivers, I would like to see them grouped by actual similarity,
> so as to not repeat the same mistakes.
> 
> I took a random feature, user port separation, and I'm comparing how Linus
> implemented it in ksz8995:
> https://lore.kernel.org/netdev/20260219-ks8995-fixups-v3-5-a7fc63fe1916@kernel.org/
> vs the register map from KSZ8463:
> https://www.microchip.com/en-us/product/ksz8463#Documentation
> 

I took a look at the register maps from both datasheets. Registers 
aren't always at the same address and some bits differ here and there 
but following areas look very similar:
- global control
- port control
- TOS priority
- MAC address config
- Indirect access
- Data rate limit

> Apart from some funky naming differences (KS8995_REG_PC1 corresponds to
> "PORT 1 CONTROL REGISTER 2"), it should be pretty similar, right? Do you
> see some differences requiring major surgery in ks8995?
> 

The biggest difference I see is the way KSZ8463 accesses the registers 
through SPI. It uses byte enable bits in the command word that don't 
exist on the other switches.

> Apart from the obvious incompleteness, of course. That driver currently
> reports DSA_TAG_PROTO_NONE. It will have to return DSA_TAG_PROTO_KS8995
> for ks8995:
> https://lore.kernel.org/netdev/20260107-ks8995-dsa-tagging-v1-1-1a92832c1540@kernel.org/
> and DSA_TAG_PROTO_KSZ9893 for your KSZ8463. Right?

Yes.

In the end, it feels OK to me to migrate KSZ8463 into ksz8863.c but it's 
hard to know for sure before actually doing it.