Clarification about dsa and ipq806x

[Rosen Penev]

On Mon, Mar 1, 2021 at 2:26 AM <ansuelsmth at gmail.com> wrote:
>
> > 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.
> >
>
> That would be the final idea but since 5.10 is a testing kernel it would be
> very good to test dsa with the other thing...
21.02 has been branched. Just convert both of them to DSA.
>
> > - 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.
> >
>
> The check if the system has dsa driver is needed only in the 02_network.
> Still don't know if it's acceptable or not.
>
> > - 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.
> >
>
> I never checked since I use a basic network config but software vlan
> should work. Dsa on 5.4 works good (it's like 2 years that I use it) but
> still the best approach would be dsa on 5.10 and keep swconfig on 5.4
>
> >
> > 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
> >
>
> Mac address is set by the gmac driver so we shouldn't have any problem
> about that.
>
> > Is setting tx-fifo-depth still necessary/ useful?
> > http://lists.infradead.org/pipermail/openwrt-devel/2020-
> > September/031417.html
> >
>
> Need to check this... In theory this is needed to set mtu to the entire
> switch. The dsa driver requires to set additional mtu as it has some
> overhead and by some logs fails to do that. So I still need to investigate
> about this.
>
> >
> > Regards
> >       Stefan Lippers-Hollmann
>
>
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