On 17.07.2018 08:50, A.s. Dong wrote:

quoted

-----Original Message-----
From: Oleksij Rempel [mailto:o.rempel at pengutronix.de]
Sent: Tuesday, July 17, 2018 2:32 PM
To: A.s. Dong <aisheng.dong@nxp.com>; Shawn Guo
[off-list ref]; Fabio Estevam [off-list ref]; Rob
Herring [off-list ref]; Mark Rutland [off-list ref]
Cc: devicetree at vger.kernel.org; kernel at pengutronix.de; linux-arm-
kernel at lists.infradead.org; dl-linux-imx [off-list ref]
Subject: Re: [PATCH v3 1/3] dt-bindings: arm: fsl: add mu binding doc



On 17.07.2018 08:26, A.s. Dong wrote:

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-----Original Message-----
From: Oleksij Rempel [mailto:o.rempel at pengutronix.de]
Sent: Tuesday, July 17, 2018 1:45 PM
To: A.s. Dong <aisheng.dong@nxp.com>; Shawn Guo
[off-list ref]; Fabio Estevam [off-list ref];

Rob

quoted

quoted

Herring [off-list ref]; Mark Rutland [off-list ref]
Cc: devicetree at vger.kernel.org; linux-arm-kernel at lists.infradead.org;
kernel at pengutronix.de; dl-linux-imx [off-list ref]
Subject: Re: [PATCH v3 1/3] dt-bindings: arm: fsl: add mu binding doc



On 17.07.2018 07:00, A.s. Dong wrote:

quoted

quoted

-----Original Message-----
From: Oleksij Rempel [mailto:o.rempel at pengutronix.de]
Sent: Monday, July 16, 2018 7:42 PM
To: Shawn Guo <shawnguo@kernel.org>; Fabio Estevam
[off-list ref]; Rob Herring [off-list ref]; Mark
Rutland [off-list ref]; A.s. Dong

[off-list ref]

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Cc: Oleksij Rempel <o.rempel@pengutronix.de>;
kernel at pengutronix.de; linux-arm-kernel at lists.infradead.org;
devicetree at vger.kernel.org;
dl-linux- imx [off-list ref]
Subject: [PATCH v3 1/3] dt-bindings: arm: fsl: add mu binding doc

The Messaging Unit module enables two processors within the SoC to
communicate and coordinate by passing messages (e.g. data, status
and
control) through the MU interface.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
 .../devicetree/bindings/mailbox/fsl,mu.txt    | 32

+++++++++++++++++++

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 1 file changed, 32 insertions(+)
 create mode 100644
Documentation/devicetree/bindings/mailbox/fsl,mu.txt

diff --git a/Documentation/devicetree/bindings/mailbox/fsl,mu.txt

b/Documentation/devicetree/bindings/mailbox/fsl,mu.txt
new file mode 100644
index 000000000000..5d48dd75b98d

--- /dev/null
+++ b/Documentation/devicetree/bindings/mailbox/fsl,mu.txt

@@ -0,0 +1,32 @@
+NXP i.MX Messaging Unit (MU)
+------------------------------------------------------------------
+--
+
+Required properties:
+-------------------
+- compatible :	should be "fsl,<chip>-mu", the supported chips

include:

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+		imx6sx	- i.MX 6SoloX
+		imx7d	- i.MX 7Dual
+		imx7s	- i.MX 7Solo
+		imx7ulp	- i.MX 7ULP
+		imx8qm	- i.MX 8QM
+		imx8qxp	- i.MX 8QXP
+- reg :		Should contain the registers location and length
+- interrupts :	Interrupt number. The interrupt specifier format

depends

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+		on the interrupt controller parent.
+- #mbox-cells:  Must be:
+		0 - for single channel mode. i.MX8* SCU protocol specific.
+		1 - for multichannel (generic) mode.
+
+Optional properties:
+-------------------
+- clocks :	phandle to the input clock.
+- fsl,mu-side-a : Should be set for side A MU.

For this property, how about doing like:
fsl,mu-side: An Integer represents the MU side.

All this SoCs have MUs with only two sides. Why do we need explicit
annotation for both parts?

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If missing this property, it's default to Side A

So, why do we need optional integer, which is set by default as side A?
This is why I made it bool.

Yes, A bool probably is better.

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	       which is mostly used by A core.

And you will need to explicit set side=B for SCU. Correct?

SCU is using side A. AFAIK all SoC A core is using side A by default.
That's why I think it can be default one. User is free to specify both
In device tree. Does it make sense to you?

Ok.

My original assumption is we can specify the side explicitly in device tree
 (default to side A if missing) like:
mu0a: mailbox at 30aa0000 {
        compatible = "fsl,imx7s-mu";
        ...
        fsl,mu-side = <0>;
};

mu0b: mailbox at 30ab0000 {
        compatible = "fsl,imx7s-mu";
        ...
        fsl,mu-side = <1>;
};

But you're right it can be simply indicated by a bool as well.
mu0a: mailbox at 30aa0000 {
        compatible = "fsl,imx7s-mu";
        ...
};

mu0b: mailbox at 30ab0000 {
        compatible = "fsl,imx7s-mu";
        ...
        fsl,mu-side-b; 
};

I'm okay with both. You can prefer as you wish.

There are advantages and disadvantages in both cases:
- bool is using less space and limited to only needed part but mistakes
can happen and some will forget to add this line.
- int part is good only if it is not optional.

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