Re: [PATCH v4 1/2] arm64: dts: lx2160a: update PCIe nodes to match rev2 silicon

From: Olof Johansson <olof@lixom.net>
To: "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc: Li Yang <leoyang.li@nxp.com>,
	shawnguo@kernel.org, devicetree@vger.kernel.org,
	 robh+dt@kernel.org, linux-arm-kernel@lists.infradead.org,
	 linux-kernel@vger.kernel.org,
	Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Subject: Re: [PATCH v4 1/2] arm64: dts: lx2160a: update PCIe nodes to match rev2 silicon
Date: Mon, 12 Sep 2022 19:34:01 -0700	[thread overview]
Message-ID: <CAOesGMh58nTcKGbNi0VzNTg3GwWM6-HZRBJPn706-6pzrpJ4Wg@mail.gmail.com> (raw)
In-Reply-To: <Yx+XonDqmpE4KGhD@shell.armlinux.org.uk>

On Mon, Sep 12, 2022 at 1:33 PM Russell King (Oracle)
<linux@armlinux.org.uk> wrote:
>
> On Mon, Sep 12, 2022 at 11:54:06AM -0700, Olof Johansson wrote:
> > On Mon, Sep 12, 2022 at 12:05 AM Olof Johansson <olof@lixom.net> wrote:
> > >
> > > Hi,
> > >
> > > On Wed, Aug 17, 2022 at 1:26 PM Li Yang <leoyang.li@nxp.com> wrote:
> > > >
> > > > The original dts was created based on the non-production rev1 silicon
> > > > which was only used for evaluation.  Update the PCIe nodes to align with
> > > > the different controller used in production rev2 silicon.
> > >
> > > How can I confirm what version of silicon I have on a system?
> > >
> > > My non-evaluation commercially purchased system (HoneyComb LX2K) has:
> > >
> > > # cat /sys/bus/soc/devices/soc0/revision
> > > 1.0
> > >
> > > And I will be really grumpy if this system stops working. It's what I
> > > use to do all my maintainer work, even if that's been fairly dormant
> > > this year.
> > >
> > > It's overall setting off red flags to update an in-place devicetree to
> > > a "new revision" of silicon instead of adding a new DT for said
> > > revision. 2160A has been on the market for several years, so it just
> > > seems odd to all of the sudden retroactively make things
> > > non-backwards-compatible.
> >
> > Confirmed that this patch renders my HoneyComb unbootable -- PCIe doesn't probe.
> >
> > Shawn, please revert, and be on the lookout for similar problematic
> > approaches in the future. Thanks!
>
> I think you may also need to beware of the MC firmware revision - I
> seem to remember reading in the changelog notes for it that NXP
> dropped support in the MC firmware for the older silicon, though I
> may be misremembering. It's been a while since I really looked at
> the LX2160A from the point of view of maintaining or developing
> anything for it.

Yeah, and if anything this speaks against trying to update u-boot/EFI
on it to something newer, bugs in firmware or not.

-Olof

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