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From:   Patrick Venture <venture@google.com>
Date:   Tue, 2 Apr 2019 14:24:29 -0700
Message-ID: <CAO=noty_jSMLatu5Z-h03hrQ=uozd1eX8SSG=iGNeB+D4W6LQw@mail.gmail.com>
Subject: Re: [PATCH v8 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support
To:     Andrew Jeffery <andrew@aj.id.au>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Joel Stanley <joel@jms.id.au>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        devicetree@vger.kernel.org,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        linux-aspeed@lists.ozlabs.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Rob Herring <robh@kernel.org>
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On Mon, Apr 1, 2019 at 8:42 PM Andrew Jeffery <andrew@aj.id.au> wrote:
>
> Hi Patrick,
>
> I held off on reviewing this until we'd hashed out what we needed in the driver.
>
> I have some comments below.
>
> On Sat, 30 Mar 2019, at 01:40, Patrick Venture wrote:
> > Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.
> >
> > Signed-off-by: Patrick Venture <venture@google.com>
> > Reviewed-by: Rob Herring <robh@kernel.org>
> > ---
> > Changes for v8:
> > - None
> > Changes for v7:
> > - Moved node under the syscon node it requires
> > Changes for v6:
> > - None
> > Changes for v5:
> > - None
> > Changes for v4:
> > - None
> > Changes for v3:
> > - None
> > Changes for v2:
> > - Added comment about syscon required parameter.
> > ---
> >  .../bindings/misc/aspeed-p2a-ctrl.txt         | 48 +++++++++++++++++++
> >  1 file changed, 48 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
> >
> > diff --git a/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
> > b/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
> > new file mode 100644
> > index 0000000000000..088cc4e3dc54b
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/misc/aspeed-p2a-ctrl.txt
> > @@ -0,0 +1,48 @@
> > +======================================================================
> > +Device tree bindings for Aspeed AST2400/AST2500 PCI-to-AHB Bridge
> > Control Driver
> > +======================================================================
> > +
> > +The bridge is available on platforms with the VGA enabled on the
> > Aspeed device.
> > +In this case, the host has access to a 64KiB window into all of the
> > BMC's
> > +memory.  The BMC can disable this bridge.  If the bridge is enabled,
> > the host
> > +has read access to all the regions of memory, however the host only
> > has read
> > +and write access depending on a register controlled by the BMC.
> > +
> > +Required properties:
> > +===================
> > +
> > + - compatible: must be one of:
> > +     - "aspeed,ast2400-p2a-ctrl"
> > +     - "aspeed,ast2500-p2a-ctrl"
> > +
> > + - syscon: handle to syscon device node controlling PCI.
>
> The p2a-ctrl node is meant to be a child of the syscon. I noted this in my review
> of the associated driver - you need to remove the description of the syscon
> property.

Roger that, I'll take a hack at cleaning this up later this week (I'm OOO).

>
> > +
> > +Optional properties:
> > +===================
> > +
> > +- memory-region: A phandle to a reserved_memory region to be used for
> > the PCI
> > +             to AHB mapping
> > +
> > +The p2a-control node should be the child of a syscon node with the
> > required
> > +property:
> > +
> > +- compatible : Should be one of the following:
> > +             "aspeed,ast2400-scu", "syscon", "simple-mfd"
> > +             "aspeed,g4-scu", "syscon", "simple-mfd"
> > +             "aspeed,ast2500-scu", "syscon", "simple-mfd"
> > +             "aspeed,g5-scu", "syscon", "simple-mfd"
>
> The note above should go where you've described the syscon property above.
>
> Cheers,
>
> Andrew
>
> > +
> > +Example:
> > +
> > +g4 Example
> > +----------
> > +
> > +syscon: scu@1e6e2000 {
> > +     compatible = "aspeed,ast2400-scu", "syscon", "simple-mfd";
> > +     reg = <0x1e6e2000 0x1a8>;
> > +
> > +     p2a: p2a-control {
> > +             compatible = "aspeed,ast2400-p2a-ctrl";
> > +             memory-region = <&reserved_memory>;
> > +     };
> > +};
> > --
> > 2.21.0.392.gf8f6787159e-goog
> >
> >