Re: [PATCH net-next 3/6] net: atm: remove support for ZeitNet ZN122x ATM devices

From: Arnd Bergmann <arnd@arndb.de>
To: Jiri Slaby <jirislaby@kernel.org>
Cc: Jakub Kicinski <kuba@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	davem@davemloft.net, pabeni@redhat.com, netdev@vger.kernel.org,
	Chas Williams <3chas3@gmail.com>,
	linux-atm-general@lists.sourceforge.net,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	linux-mips@vger.kernel.org
Subject: Re: [PATCH net-next 3/6] net: atm: remove support for ZeitNet ZN122x ATM devices
Date: Thu, 11 Aug 2022 11:18:42 +0200	[thread overview]
Message-ID: <CAK8P3a1E=e5YNj9i0nwj=D=xBg=gi8AqfDcMwZpGCNn81+v5cQ@mail.gmail.com> (raw)
In-Reply-To: <de3170f3-6035-21e4-8ca5-427ca878b3a4@kernel.org>

On Thu, Aug 11, 2022 at 7:19 AM Jiri Slaby <jirislaby@kernel.org> wrote:
> On 10. 08. 22, 18:42, Jakub Kicinski wrote:
> > On Wed, 10 Aug 2022 11:11:32 +0200 Arnd Bergmann wrote:
> >>> This unfortunately breaks linux-atm:
> >>> zntune.c:18:10: fatal error: linux/atm_zatm.h: No such file or directory
> >>>
> >>> The source does also:
> >>> ioctl(s,ZATM_SETPOOL,&sioc)
> >>> ioctl(s,zero ? ZATM_GETPOOLZ : ZATM_GETPOOL,&sioc)
> >>> etc.
> >>>
> >>> So we should likely revert the below:
> >>
> >> I suppose there is no chance of also getting the linux-atm package updated
> >> to not include those source files, right? The last release I found on
> >> sourceforge
> >> is 12 years old, but maybe I was looking in the wrong place.
> >
> > Is linux-atm used for something remotely modern? PPPoA? Maybe it's
> > time to ditch it completely? I'll send the revert in any case.
>
> Sorry, I have no idea. openSUSE is just a provider of an rpm -- if there
> any users? Who knows...

I think in theory this is the subsystem that DSL drivers would use, but
there is only one driver for the "Solos ADSL2+".

OpenWRT used to support the TI AR7 platform (later owned by Infineon,
Lantiq, and Intel, now Maxlinear) with the "sangam-atm" driver for DSL,
but that driver was never available in mainline Linux and is now gone
from OpenWRT as well.

It appears that the later hardware that is still supported uses a custom
atm driver implementation rather than the in-kernel subsystem, using
a different set of ioctls:
https://git.openwrt.org/?p=openwrt/openwrt.git;a=tree;f=package/kernel/lantiq/ltq-atm/src

There are also DSL SoCs from (at least) Broadcom, Realtek, Mediatek and
Qualcomm, but no open source drivers, so I guess they probably all
use their own kernel subsystems.

       Arnd