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From: Gerhard Engleder <gerhard@engleder-embedded.com>
To: Michal Simek <michal.simek@xilinx.com>
Cc: Rob Herring <robh+dt@kernel.org>,
	David Miller <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, netdev <netdev@vger.kernel.org>,
	devicetree@vger.kernel.org
Subject: Re: [PATCH net-next 2/5] dt-bindings: net: Add tsnep Ethernet controller
Date: Wed, 28 Jul 2021 22:14:12 +0200	[thread overview]
Message-ID: <CANr-f5y4=1hj-6WFT1HdewU=sich6KgkgmR6-qWimFxQiV5MFQ@mail.gmail.com> (raw)
In-Reply-To: <b3921ff3-55d4-0d26-ebe3-2fee0c73332e@xilinx.com>

On Wed, Jul 28, 2021 at 12:55 PM Michal Simek <michal.simek@xilinx.com> wrote:
> >>>>>> +      - enum:
> >>>>>> +        - engleder,tsnep
> >>>>>
> >>>>> tsnep is pretty generic. Only 1 version ever? Or differences are/will
> >>>>> be discoverable by other means.
> >>>>
> >>>> Differences shall be detected by flags in the registers; e.g., a flag for
> >>>> gate control support. Anyway a version may make sense. Can you
> >>>> point to a good reference binding with versions? I did not find a
> >>>> network controller binding with versions.
> >>>
> >>> Some of the SiFive IP blocks have versions. Version numbers are the
> >>> exception though. Ideally they would correspond to some version of
> >>> your FPGA image. I just don't want to see 'v1' because that sounds
> >>> made up. The above string can mean 'v1' or whatever version you want.
> >>> I'm fine if you just add some description here about feature flag
> >>> registers.
> >>
> >> Don't Xilinx design tool (vivado) force you to use IP version?
> >> Normally all Xilinx IPs have certain version because that's the only way
> >> how to manage it.
> >
> > Yes I use an IP version in the Xilinx design tool. I use it as a version of the
> > VHDL code itself. In my case this version is not related to the
> > hardware software
> > interface. The goal is to keep the hardware software interface compatible, so
> > the IP version should not be relevant.
>
> I expect this is goal for everybody but it fails over time. We normally
> compose compatible string for PL based IP with IP version which is used.
> And it is quite common that couple of HW version are SW compatible to
> each other.
> It means use the same HW version as you use now. When you reach the
> point when your HW IP needs to be upgraded and will require SW alignment
> you have versions around which can be used directly.

I would like to follow the argument from Rob:
"The above string can mean 'v1' or whatever version you want."
If there ever is an incompatible new IP version, then a new compatible string
can be added which means 'v2'. E.g. for 128bit physical address support I
would choose the compatible string 'engleder,tsnep128'. I don't see an
advantage in adding a version number to the compatible string.

This IP will be used in products where compatible hardware is a must.
An IP upgrade which requires SW alignment will result in heavy complaints
from the customers. Such an IP upgrade would result in a new IP.
Like for shared libraries, an incompatible API change is similar to a new
library.

Gerhard

  reply	other threads:[~2021-07-28 20:14 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-26 19:45 [PATCH net-next 0/5] TSN endpoint Ethernet MAC driver Gerhard Engleder
2021-07-26 19:45 ` [PATCH net-next 1/5] dt-bindings: Add vendor prefix for Engleder Gerhard Engleder
2021-07-26 19:46 ` [PATCH net-next 2/5] dt-bindings: net: Add tsnep Ethernet controller Gerhard Engleder
2021-07-26 23:35   ` Rob Herring
2021-07-27 18:34     ` Gerhard Engleder
2021-07-27 20:25       ` Rob Herring
2021-07-27 20:33         ` Gerhard Engleder
2021-07-28  5:13         ` Michal Simek
2021-07-28  7:44           ` Gerhard Engleder
2021-07-28 10:55             ` Michal Simek
2021-07-28 20:14               ` Gerhard Engleder [this message]
2021-07-29  5:07                 ` Michal Simek
2021-07-29  7:07                   ` Gerhard Engleder
2021-07-29  7:57                     ` Michal Simek
2021-07-26 19:46 ` [PATCH net-next 3/5] dt-bindings: arm: Add Engleder bindings Gerhard Engleder
2021-07-26 19:46 ` [PATCH net-next 4/5] tsnep: Add TSN endpoint Ethernet MAC driver Gerhard Engleder
2021-07-26 20:49   ` Andrew Lunn
2021-07-27 20:18     ` Gerhard Engleder
2021-07-26 21:15   ` Andrew Lunn
2021-07-27 20:49     ` Gerhard Engleder
2021-07-26 21:29   ` Andrew Lunn
2021-07-27 22:05     ` Gerhard Engleder
2021-07-27 22:41       ` Andrew Lunn
2021-07-28  8:24         ` Gerhard Engleder
2021-07-26 23:25   ` kernel test robot
2021-07-26 19:46 ` [PATCH net-next 5/5] arm64: dts: zynqmp: Add ZCU104 based TSN endpoint Gerhard Engleder
2021-07-26 23:40   ` Rob Herring
2021-07-27 20:10     ` Gerhard Engleder
2021-07-27 20:17       ` Rob Herring
2021-07-27 20:23         ` Gerhard Engleder
2021-07-28  5:10           ` Michal Simek
2021-07-28  8:19             ` Gerhard Engleder
2021-07-28 10:58               ` Michal Simek
2021-07-28 20:51                 ` Gerhard Engleder
2021-07-29  5:22                   ` Michal Simek
2021-07-29  6:47                     ` Gerhard Engleder

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