netdev - Re: [PATCH net-next] dt-bindings: net: marvell,orion-mdio: Drop "reg" sizes schema

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Date: Fri, 15 Dec 2023 09:41:15 -0600
From: Rob Herring <robh@...nel.org>
To: Andrew Lunn <andrew@...n.ch>
Cc: Conor Dooley <conor@...nel.org>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	netdev@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] dt-bindings: net: marvell,orion-mdio: Drop "reg"
 sizes schema

On Fri, Dec 15, 2023 at 4:18 AM Andrew Lunn <andrew@...n.ch> wrote:
>
> On Thu, Dec 14, 2023 at 12:12:42PM -0600, Rob Herring wrote:
> > On Thu, Dec 14, 2023 at 10:23 AM Conor Dooley <conor@...nel.org> wrote:
> > >
> > > On Wed, Dec 13, 2023 at 05:24:55PM -0600, Rob Herring wrote:
> > > > Defining the size of register regions is not really in scope of what
> > > > bindings need to cover. The schema for this is also not completely correct
> > > > as a reg entry can be variable number of cells for the address and size,
> > > > but the schema assumes 1 cell.
> > > >
> > > > Signed-off-by: Rob Herring <robh@...nel.org>
> > >
> > > Does this not also remove restrictions on what the number in the reg
> > > entry is actually allowed to be?
> >
> > Yes, that's what I mean with the first sentence. We don't do this
> > anywhere else with the exception of some I2C devices with fixed
> > addresses. Keying off of the interrupt property also seems
> > questionable. If the register size is different, that should be a
> > different compatible.
>
> Reading the code, it appears the hardware always supported interrupts,
> however the first version of the driver never used them. It seems like
> some DT blobs had the register space cover just the needed registers
> for polling, and excluded the interrupt control register. When
> interrupt support was added, all in-tree DT files were updated with
> the extended register space, but to allow backwards compatibility, the
> driver checks the length of the register space and will not enable
> interrupts if its too small.
>
> I'm guessing that since the hardware did not change, a new compatible
> was not used when adding interrupt support. And the yaml is there to
> help when old out of tree .dts files are merged into the tree and have
> the old register space.
>
> This is and old driver, and its usage of DT is from long before many
> of the current best practices where determined, or yaml was even an
> idea. So i'm not surprised it has a few odd quirks.
>
> I don't see a reason not to remove these constraints, as i said, the
> driver should do the right thing if the register space it too small
> and YAML does not warn about it.

Is that an Ack? I almost read your double negative as a Nak and that's
what the maintainers read because it is now "Rejected" in PW.

Rob