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Date:   Thu, 5 May 2022 17:47:15 +0200
From:   Pali =?utf-8?B?Um9ow6Fy?= <pali@kernel.org>
To:     Rob Herring <robh+dt@kernel.org>
Cc:     Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] powerpc/85xx: P2020: Add law_trgt_if property to PCIe DT
 nodes
Message-ID: <20220505154715.xujvyjvewsj6jcw7@pali>
References: <20220504180822.29782-1-pali@kernel.org>
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On Thursday 05 May 2022 10:40:09 Rob Herring wrote:
> On Wed, May 4, 2022 at 1:09 PM Pali Rohár <pali@kernel.org> wrote:
> >
> > DT law_trgt_if property defines Local Access Window Target Interface.
> 
> Documentation?

I was not able to find it :-( So the only documentation for me was the
source code and decoding how it works and how it is used.

> fsl,law-trgt-if would be the preferred form.
> 
> > Local Access Window Target Interface is used for identifying individual
> > peripheral and mapping its memory to CPU. Interface id is defined by
> > hardware itself.
> 
> Normally, we avoid instance indices like this, but if it is more than
> just documentation convention maybe that's fine.
> 
> Rob

It is id defined by HW. Software needs to know how to pair DT node with
address range defined in "ranges" to the correct HW PCIe controller.