[PATCH v8 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

[PATCH v8 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

[Patrick Venture]

Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.

Signed-off-by: Patrick Venture <venture@google.com>
---
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.
+
+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"
+
+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

Re: [PATCH v8 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

[Rob Herring]

On Wed, 27 Mar 2019 14:21:55 -0700, Patrick Venture wrote:
> Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.
> 
> Signed-off-by: Patrick Venture <venture@google.com>
> ---
> 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
> 

Please add Acked-by/Reviewed-by tags when posting new versions. However,
there's no need to repost patches *only* to add the tags. The upstream
maintainer will do that for acks received on the version they apply.

If a tag was not added on purpose, please state why and what changed.

Re: [PATCH v8 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

[Patrick Venture]

On Thu, Mar 28, 2019 at 9:50 AM Rob Herring <robh@kernel.org> wrote:
>
> On Wed, 27 Mar 2019 14:21:55 -0700, Patrick Venture wrote:
> > Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.
> >
> > Signed-off-by: Patrick Venture <venture@google.com>
> > ---
> > 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
> >
>
> Please add Acked-by/Reviewed-by tags when posting new versions. However,
> there's no need to repost patches *only* to add the tags. The upstream
> maintainer will do that for acks received on the version they apply.
>
> If a tag was not added on purpose, please state why and what changed.

Adding tags in this case is adding a change version?  I was doing this
to keep the two patches version-synced.  I thought that was required.
There was a version change in the other patch in this set.

Re: [PATCH v8 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

[Rob Herring]

On Thu, Mar 28, 2019 at 12:03 PM Patrick Venture <venture@google.com> wrote:
>
> On Thu, Mar 28, 2019 at 9:50 AM Rob Herring <robh@kernel.org> wrote:
> >
> > On Wed, 27 Mar 2019 14:21:55 -0700, Patrick Venture wrote:
> > > Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.
> > >
> > > Signed-off-by: Patrick Venture <venture@google.com>
> > > ---
> > > 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
> > >
> >
> > Please add Acked-by/Reviewed-by tags when posting new versions. However,
> > there's no need to repost patches *only* to add the tags. The upstream
> > maintainer will do that for acks received on the version they apply.
> >
> > If a tag was not added on purpose, please state why and what changed.
>
> Adding tags in this case is adding a change version?  I was doing this
> to keep the two patches version-synced.  I thought that was required.
> There was a version change in the other patch in this set.

Adding tags is not considered a change. I gave a Reviewed-by in v7.
Subsequent versions should carry that tag if there's no change (or
only minor changes) in this patch. What happens in the other patches
is not really important. Maintainers are not going to go searching
thru the versions to find all the ack/review tags. And if I've already
reviewed this, I don't want to look at it again.

Rob

Re: [PATCH v8 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

[Patrick Venture]

On Fri, Mar 29, 2019 at 6:38 AM Rob Herring <robh@kernel.org> wrote:
>
> On Thu, Mar 28, 2019 at 12:03 PM Patrick Venture <venture@google.com> wrote:
> >
> > On Thu, Mar 28, 2019 at 9:50 AM Rob Herring <robh@kernel.org> wrote:
> > >
> > > On Wed, 27 Mar 2019 14:21:55 -0700, Patrick Venture wrote:
> > > > Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.
> > > >
> > > > Signed-off-by: Patrick Venture <venture@google.com>
> > > > ---
> > > > 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
> > > >
> > >
> > > Please add Acked-by/Reviewed-by tags when posting new versions. However,
> > > there's no need to repost patches *only* to add the tags. The upstream
> > > maintainer will do that for acks received on the version they apply.
> > >
> > > If a tag was not added on purpose, please state why and what changed.
> >
> > Adding tags in this case is adding a change version?  I was doing this
> > to keep the two patches version-synced.  I thought that was required.
> > There was a version change in the other patch in this set.
>
> Adding tags is not considered a change. I gave a Reviewed-by in v7.
> Subsequent versions should carry that tag if there's no change (or
> only minor changes) in this patch. What happens in the other patches
> is not really important. Maintainers are not going to go searching
> thru the versions to find all the ack/review tags. And if I've already
> reviewed this, I don't want to look at it again.

Thank you, I didn't realize that had happened.

>
> Rob

Re: [PATCH v8 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

[Patrick Venture]

On Fri, Mar 29, 2019 at 7:56 AM Patrick Venture <venture@google.com> wrote:
>
> On Fri, Mar 29, 2019 at 6:38 AM Rob Herring <robh@kernel.org> wrote:
> >
> > On Thu, Mar 28, 2019 at 12:03 PM Patrick Venture <venture@google.com> wrote:
> > >
> > > On Thu, Mar 28, 2019 at 9:50 AM Rob Herring <robh@kernel.org> wrote:
> > > >
> > > > On Wed, 27 Mar 2019 14:21:55 -0700, Patrick Venture wrote:
> > > > > Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.
> > > > >
> > > > > Signed-off-by: Patrick Venture <venture@google.com>
> > > > > ---
> > > > > 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
> > > > >
> > > >
> > > > Please add Acked-by/Reviewed-by tags when posting new versions. However,
> > > > there's no need to repost patches *only* to add the tags. The upstream
> > > > maintainer will do that for acks received on the version they apply.
> > > >
> > > > If a tag was not added on purpose, please state why and what changed.
> > >
> > > Adding tags in this case is adding a change version?  I was doing this
> > > to keep the two patches version-synced.  I thought that was required.
> > > There was a version change in the other patch in this set.
> >
> > Adding tags is not considered a change. I gave a Reviewed-by in v7.
> > Subsequent versions should carry that tag if there's no change (or
> > only minor changes) in this patch. What happens in the other patches
> > is not really important. Maintainers are not going to go searching
> > thru the versions to find all the ack/review tags. And if I've already
> > reviewed this, I don't want to look at it again.
>
> Thank you, I didn't realize that had happened.

I went back through my email and found the line of your email that
included it.  I apologize.

So, before I send the updated patch with your ack -- do I need to send
a v9? or is this just me sending v8 again?

>
> >
> > Rob

Re: [PATCH v8 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

[Patrick Venture]

On Fri, Mar 29, 2019 at 7:59 AM Patrick Venture <venture@google.com> wrote:
>
> On Fri, Mar 29, 2019 at 7:56 AM Patrick Venture <venture@google.com> wrote:
> >
> > On Fri, Mar 29, 2019 at 6:38 AM Rob Herring <robh@kernel.org> wrote:
> > >
> > > On Thu, Mar 28, 2019 at 12:03 PM Patrick Venture <venture@google.com> wrote:
> > > >
> > > > On Thu, Mar 28, 2019 at 9:50 AM Rob Herring <robh@kernel.org> wrote:
> > > > >
> > > > > On Wed, 27 Mar 2019 14:21:55 -0700, Patrick Venture wrote:
> > > > > > Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.
> > > > > >
> > > > > > Signed-off-by: Patrick Venture <venture@google.com>
> > > > > > ---
> > > > > > 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
> > > > > >
> > > > >
> > > > > Please add Acked-by/Reviewed-by tags when posting new versions. However,
> > > > > there's no need to repost patches *only* to add the tags. The upstream
> > > > > maintainer will do that for acks received on the version they apply.
> > > > >
> > > > > If a tag was not added on purpose, please state why and what changed.
> > > >
> > > > Adding tags in this case is adding a change version?  I was doing this
> > > > to keep the two patches version-synced.  I thought that was required.
> > > > There was a version change in the other patch in this set.
> > >
> > > Adding tags is not considered a change. I gave a Reviewed-by in v7.
> > > Subsequent versions should carry that tag if there's no change (or
> > > only minor changes) in this patch. What happens in the other patches
> > > is not really important. Maintainers are not going to go searching
> > > thru the versions to find all the ack/review tags. And if I've already
> > > reviewed this, I don't want to look at it again.
> >
> > Thank you, I didn't realize that had happened.
>
> I went back through my email and found the line of your email that
> included it.  I apologize.
>
> So, before I send the updated patch with your ack -- do I need to send
> a v9? or is this just me sending v8 again?

Sorry.  I see you already answered that when you said that adding a
tag isn't considered a change.  I have therefore re-sent v8 of this
patch with your tag added.

>
> >
> > >
> > > Rob

Re: [PATCH v8 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

[Rob Herring]

On Fri, Mar 29, 2019 at 10:11 AM Patrick Venture <venture@google.com> wrote:
>
> On Fri, Mar 29, 2019 at 7:59 AM Patrick Venture <venture@google.com> wrote:
> >
> > On Fri, Mar 29, 2019 at 7:56 AM Patrick Venture <venture@google.com> wrote:
> > >
> > > On Fri, Mar 29, 2019 at 6:38 AM Rob Herring <robh@kernel.org> wrote:
> > > >
> > > > On Thu, Mar 28, 2019 at 12:03 PM Patrick Venture <venture@google.com> wrote:
> > > > >
> > > > > On Thu, Mar 28, 2019 at 9:50 AM Rob Herring <robh@kernel.org> wrote:
> > > > > >
> > > > > > On Wed, 27 Mar 2019 14:21:55 -0700, Patrick Venture wrote:
> > > > > > > Document the ast2400, ast2500 PCI-to-AHB bridge control driver bindings.
> > > > > > >
> > > > > > > Signed-off-by: Patrick Venture <venture@google.com>
> > > > > > > ---
> > > > > > > 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
> > > > > > >
> > > > > >
> > > > > > Please add Acked-by/Reviewed-by tags when posting new versions. However,
> > > > > > there's no need to repost patches *only* to add the tags. The upstream
> > > > > > maintainer will do that for acks received on the version they apply.
> > > > > >
> > > > > > If a tag was not added on purpose, please state why and what changed.
> > > > >
> > > > > Adding tags in this case is adding a change version?  I was doing this
> > > > > to keep the two patches version-synced.  I thought that was required.
> > > > > There was a version change in the other patch in this set.
> > > >
> > > > Adding tags is not considered a change. I gave a Reviewed-by in v7.
> > > > Subsequent versions should carry that tag if there's no change (or
> > > > only minor changes) in this patch. What happens in the other patches
> > > > is not really important. Maintainers are not going to go searching
> > > > thru the versions to find all the ack/review tags. And if I've already
> > > > reviewed this, I don't want to look at it again.
> > >
> > > Thank you, I didn't realize that had happened.
> >
> > I went back through my email and found the line of your email that
> > included it.  I apologize.
> >
> > So, before I send the updated patch with your ack -- do I need to send
> > a v9? or is this just me sending v8 again?
>
> Sorry.  I see you already answered that when you said that adding a
> tag isn't considered a change.  I have therefore re-sent v8 of this
> patch with your tag added.

To repeat my form letter again, you don't need to send a series again
just to add tags. IOW, if you send a v9, then add the tags. If v8 is
what a maintainer applies, the maintain will take care of adding them
(or patchwork does it for us):

> Please add Acked-by/Reviewed-by tags when posting new versions. However,
> there's no need to repost patches *only* to add the tags. The upstream
> maintainer will do that for acks received on the version they apply.

Re: [PATCH v8 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

[Patrick Venture]

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
> >
> >

Re: [PATCH v8 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

[Andrew Jeffery]

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.

> +
> +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
> 
>

[PATCH v8 1/2] dt-bindings: misc: aspeed-p2a-ctrl: add support

[Patrick Venture]

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.
+
+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"
+
+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