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From: Hans Schultz <netdev@kapio-technology.com>
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Date: Tue, 14 Feb 2023 22:14:55 +0100
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Subject: Re: [Bridge] [PATCH net-next 5/5] net: dsa: mv88e6xxx:
 implementation of dynamic ATU entries
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To: Simon Horman <simon.horman@corigine.com>
Cc: Andrew Lunn <andrew@lunn.ch>, Alexandre Belloni <alexandre.belloni@bootlin.com>, Nikolay Aleksandrov <razor@blackwall.org>, Kurt Kanzenbach <kurt@linutronix.de>, Eric Dumazet <edumazet@google.com>, Ivan Vecera <ivecera@redhat.com>, Florian Fainelli <f.fainelli@gmail.com>, "moderated list:ETHERNET BRIDGE" <bridge@lists.linux-foundation.org>, Russell King <linux@armlinux.org.uk>, Roopa Prabhu <roopa@nvidia.com>, kuba@kernel.org, Paolo Abeni <pabeni@redhat.com>, =?utf-8?Q?Cl=C3=A9ment_L=C3=A9ger?= <clement.leger@bootlin.com>, Christian Marangi <ansuelsmth@gmail.com>, Woojung Huh <woojung.huh@microchip.com>, Landen Chao <Landen.Chao@mediatek.com>, Jiri Pirko <jiri@resnulli.us>, Hauke Mehrtens <hauke@hauke-m.de>, Sean Wang <sean.wang@mediatek.com>, DENG Qingfang <dqfext@gmail.com>, Claudiu Manoil <claudiu.manoil@nxp.com>, "moderated list:ARM/Mediatek SoC
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On Mon, Feb 06, 2023 at 17:02, Simon Horman <simon.horman@corigine.com> wrote:
>
> Just to clarify my suggestion one last time, it would be along the lines
> of the following (completely untested!). I feel that it robustly covers
> all cases for fdb_flags. And as a bonus doesn't need to be modified
> if other (unsupported) flags are added in future.
>
> 	if (fdb_flags & ~(DSA_FDB_FLAG_DYNAMIC))
> 		return -EOPNOTSUPP;
>
> 	is_dynamic = !!(fdb_flags & DSA_FDB_FLAG_DYNAMIC)
> 	if (is_dynamic)
> 		state = MV88E6XXX_G1_ATU_DATA_STATE_UC_AGE_7_NEWEST;
>
>
> And perhaps for other drivers:
>
> 	if (fdb_flags & ~(DSA_FDB_FLAG_DYNAMIC))
> 		return -EOPNOTSUPP;
> 	if (fdb_flags)
> 		return 0;
>
> Perhaps a helper would be warranted for the above.

How would such a helper look? Inline function is not clean.

>
> But in writing this I think that, perhaps drivers could return -EOPNOTSUPP
> for the DSA_FDB_FLAG_DYNAMIC case and the caller can handle, rather tha
> propagate, -EOPNOTSUPP.

I looked at that, but changing the caller is also a bit ugly.

>
> Returning -EOPNOTSUPP is the normal way to drivers to respond to requests
> for unsupported hardware offloads. Sticking to that may be clearner
> in the long run. That said, I do agree your current patch is correct
> given the flag that is defined (by your patchset).