Clarification about dsa and ipq806x

[Stefan Lippers-Hollmann]

Hi

[Disclaimer: I'm not an OpenWrt developer]

On 2021-03-01, Ansuel Smith wrote:
[...]
> The idea is to switch this target to dsa but there is a problem...
> Since kernel 5.10 is a testing kernel how should I change the base
[...]
> Do we have some way in openwrt to know if the system use dsa driver or
> swconfig driver?

I could come up with these strategies:

- if swconfig is still working in v5.10 with reasonable efforts, the
  easy way out could be to stick with swconfig for the TESTING_KERNEL
  introduction - and switch over to DSA as soon as it is acceptable to
  get rid of kernel v5.4.

- adding kernel version based conditionals to
  - target/linux/ipq806x/base-files/etc/board.d/02_network
  - target/linux/ipq806x/base-files/etc/board.d/05_compat-version (new)
  - target/linux/ipq806x/image/Makefile (checking for TESTING_KERNEL)
  and toggling DEVICE_COMPAT_VERSION between them as needed. This
  does require (and enforces via DEVICE_COMPAT_VERSION) nuking the
  existing configuration between v5.4 and v5.10 based builds, but would
  allow building either from the same source.

- if DSA is mostly working on kernel v5.4 (or could be retrofitted
  *easily*), switching kernel v5.4 in master over to DSA might be
  another option.
  "the dsa driver still lacks vlan support in kernel 5.4" suggests
  that this wouldn't be a reasonable option though.


Just two questions of my own.

I think to remember that introducing DSA based drivers is slightly at
odds with devices storing the MAC address in ASCII representation
(uboot-env) rather than binary at a fixed offset, is that an issue
here?
This affects linksys,ea7500-v1, linksys,ea8500 and zyxel,nbg6817

Is setting tx-fifo-depth still necessary/ useful?
http://lists.infradead.org/pipermail/openwrt-devel/2020-September/031417.html


Regards
	Stefan Lippers-Hollmann