linux-kernel - Re: [RFC-ish PATCH 00/17] Clean up ASPEED devicetree warnings

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Message-Id: <fd8e57f0-aee2-403e-b6fb-76d0c18fe306@www.fastmail.com>
Date:   Tue, 30 Jul 2019 10:39:50 +0930
From:   "Andrew Jeffery" <andrew@...id.au>
To:     "Rob Herring" <robh+dt@...nel.org>
Cc:     linux-aspeed@...ts.ozlabs.org,
        "Mark Rutland" <mark.rutland@....com>,
        "Joel Stanley" <joel@....id.au>, devicetree@...r.kernel.org,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Adriana Kobylak" <anoo@...ibm.com>,
        "Alexander A. Filippov" <a.filippov@...ro.com>,
        "Arnd Bergmann" <arnd@...db.de>,
        YangBrianC.W 楊嘉偉 TAO 
        <yang.brianc.w@...entec.com>, "Corey Minyard" <minyard@....org>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
        "Haiyue Wang" <haiyue.wang@...ux.intel.com>,
        "John Wang" <wangzqbj@...pur.com>,
        "Ken Chen" <chen.kenyy@...entec.com>,
        "Linus Walleij" <linus.walleij@...aro.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        openipmi-developer@...ts.sourceforge.net,
        "Patrick Venture" <venture@...gle.com>,
        "Stefan M Schaeckeler" <sschaeck@...co.com>,
        "Tao Ren" <taoren@...com>, "Xo Wang" <xow@...gle.com>,
        yao.yuan@...aro.org
Subject: Re: [RFC-ish PATCH 00/17] Clean up ASPEED devicetree warnings



On Tue, 30 Jul 2019, at 10:23, Rob Herring wrote:
> On Thu, Jul 25, 2019 at 11:40 PM Andrew Jeffery <andrew@...id.au> wrote:
> >
> > Hello,
> >
> > The aim of this series is to minimise/eliminate all the warnings from the
> > ASPEED devicetrees. It mostly achieves its goal, as outlined below.
> >
> > Using `aspeed_g5_defconfig` we started with the follow warning count:
> >
> >     $ make dtbs 2>&1 >/dev/null | wc -l
> >     218
> >
> > and after the full series is applied we have:
> >
> >     $ make dtbs 2>&1 >/dev/null | wc -l
> >     2
> >
> > for a 100x reduction.
> >
> > Getting there though isn't without some potential controversy, which I've saved
> > for the last half of the series. The following patches I think are in pretty
> > good shape:
> >
> >   ARM: dts: aspeed-g5: Move EDAC node to APB
> >   ARM: dts: aspeed-g5: Use recommended generic node name for SDMC
> >   ARM: dts: aspeed-g5: Fix aspeed,external-nodes description
> >   ARM: dts: vesnin: Add unit address for memory node
> >   ARM: dts: fp5280g2: Cleanup gpio-keys-polled properties
> >   ARM: dts: swift: Cleanup gpio-keys-polled properties
> >   ARM: dts: witherspoon: Cleanup gpio-keys-polled properties
> >   ARM: dts: aspeed: Cleanup lpc-ctrl and snoop regs
> >   ARM: dts: ibm-power9-dual: Add a unit address for OCC nodes
> >
> > With these patches applied we get to:
> >
> >     $ make dtbs 2>&1 >/dev/null | wc -l
> >     144
> >
> > So they make a dent, but fail to clean up the bulk of the issues. From here
> > I've mixed in some binding and driver changes with subsequent updates to the
> > devicetrees:
> >
> >   dt-bindings: pinctrl: aspeed: Add reg property as a hint
> >   dt-bindings: misc: Document reg for aspeed,p2a-ctrl nodes
> >   ARM: dts: aspeed: Add reg hints to syscon children
> >   dt-bindings: ipmi: aspeed: Introduce a v2 binding for KCS
> >   ipmi: kcs: Finish configuring ASPEED KCS device before enable
> >   ipmi: kcs: aspeed: Implement v2 bindings
> >   ARM: dts: aspeed-g5: Change KCS nodes to v2 binding
> >   ARM: dts: aspeed-g5: Sort LPC child nodes by unit address
> >
> > By `dt-bindings: ipmi: aspeed: Introduce a v2 binding for KCS` the warnings are
> > reduced to:
> >
> >     $ make dtbs 2>&1 >/dev/null | wc -l
> >     125
> >
> > The bang-for-buck is in fixing up the KCS bindings which removes all-but-two of
> > the remaining warnings (which we can't feasibly remove), but doing so forces
> > code changes (which I'd avoided up until this point).
> >
> > Reflecting broadly on the fixes, I think I've made a mistake way back by using
> > syscon/simple-mfds to expose the innards of the SCU and LPC controllers in the
> > devicetree. This series cleans up what's currently there, but I have half a
> > mind to rev the SCU and LPC bindings to not use simple-mfd and instead have a
> > driver implementation that uses `platform_device_register_full()` or similar to
> > deal with the mess.
> >
> > Rob - I'm looking for your thoughts here and on the series, I've never felt
> > entirely comfortable with what I cooked up. Your advice would be appreciated.
> 
> The series generally looks fine to me from a quick scan. As far as
> dropping 'simple-mfd', having less fine grained description in DT is
> generally my preference. It comes down to whether what you have
> defined is maintainable. As most of it is just additions, I think what
> you have is fine. Maybe keep all this in mind for the next chip
> depending how the SCU and LPC change.

Okay, I think the timing of that suggestion is good given where things are with
the AST2600. I'll keep that in mind.

Consensus so far seems to be that the series is fine. I'll split it up and send out
the sub-series to the relevant lists with the acks accumulated here.

Thanks all for taking a look.

Andrew