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

[Leo Li]

> -----Original Message-----
> From: Olof Johansson <olof@xxxxxxxxx>
> Sent: Monday, September 12, 2022 2:05 AM
> To: Leo Li <leoyang.li@xxxxxxx>
> Cc: shawnguo@xxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx;
> robh+dt@xxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; Z.Q. Hou <zhiqiang.hou@xxxxxxx>
> Subject: Re: [PATCH v4 1/2] arm64: dts: lx2160a: update PCIe nodes to match
> rev2 silicon
> 
> Hi,
> 
> On Wed, Aug 17, 2022 at 1:26 PM Li Yang <leoyang.li@xxxxxxx> 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.

Some more background information.  The Rev1 silicon was only shipped for a very short period of time(for evaluation purpose only from what I heard) before the rev2 was out to fix some critical hardware issues.  And we have recommended all customers to switch to Rev2 to avoid potential issues in Rev1.  This non-backwards-compatible change is to avoid the potential confusion between rev1 and rev2 on assumption that there is no remaining users of Rev1 now, which seems to be not the case according to your response.

Regards,
Leo