linux-kernel - Re: [PATCH v1 1/2] remoteproc: dt: Provide bindings for iMX6SX/7D Remote Processor Controller driver

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Message-ID: <91bfe236-0410-b26e-7ef6-73d14ebf120d@pengutronix.de>
Date:   Tue, 18 Jul 2017 10:45:19 +0200
From:   Oleksij Rempel <ore@...gutronix.de>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Oleksij Rempel <o.rempel@...gutronix.de>
Cc:     devicetree@...r.kernel.org, kernel@...gutronix.de,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@...linux.org.uk>,
        Shawn Guo <shawnguo@...nel.org>,
        Fabio Estevam <fabio.estevam@....com>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        linux-remoteproc@...r.kernel.org, linux@...pel-privat.de
Subject: Re: [PATCH v1 1/2] remoteproc: dt: Provide bindings for iMX6SX/7D
 Remote Processor Controller driver

Hallo Bjorn,

On 11.07.2017 00:14, Bjorn Andersson wrote:
> On Mon 10 Jul 07:42 PDT 2017, Oleksij Rempel wrote:
>
>> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
>> ---
>>  .../devicetree/bindings/remoteproc/imx-rproc.txt   | 44 ++++++++++++++++++++++
>>  1 file changed, 44 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/remoteproc/imx-rproc.txt
>>
>> diff --git a/Documentation/devicetree/bindings/remoteproc/imx-rproc.txt b/Documentation/devicetree/bindings/remoteproc/imx-rproc.txt
>> new file mode 100644
>> index 000000000000..e7c61993e1b8
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/remoteproc/imx-rproc.txt
>> @@ -0,0 +1,44 @@
>> +NXP iMX6SX/iMX7D Co-Processor Bindings
>> +----------------------------------------
>> +
>> +This binding provides support for ARM Cortex M4 Co-processor found on some
>> +NXP iMX SoCs.
>> +
>> +Required properties:
>> +- compatible		Should be one of:
>> +				"fsl,imx7d-rproc"
>> +				"fsl,imx6sx-rproc"
>> +- clocks		Clock for co-processor (See: ../clock/clock-bindings.txt)
>> +- syscfg		Phandle to syscon block which provide access to
>
> This is called "syscon" in the code and the example.

done.

>> +			System Reset Controller
>> +
>> +Optional properties:
>> +- reg:			Should contain the address ranges for some of internal
>> +			memory regions.
>
> Something less hand-wavy, like: "Should list the memory regions for the
> remoteproc"
>
>> +- reg-names:		Contains the corresponding names for the memory
>> +			regions. These should be named "ddr", "ocram", "ocram-s",
>> +			"ocram-epdc" or "ocram-pxp".
>
> Make this comment define which memory regions are required for each of
> the systems.

done.

>> +Fallowing memory ranges are expected:
>> +- For "fsl,imx7d-rproc"
>> +	<0x00900000 0x00020000> - "ocram"
>> +	<0x00920000 0x00020000> - "ocram-epdc"
>> +	<0x00940000 0x00008000> - "ocram-pxp"
>> +	<0x80000000 0x0FFF0000> - "ddr" (code area)
>> +	<0x80000000 0x60000000> - "ddr" (data area)
>
> There's no reason to list the actual regions in the binding
> document. Just list the requires regions for each system.
>
>> +- For "fsl,imx6sx-rproc"
>> +	<0x008F8000 0x00004000> - "ocram-s"
>> +	<0x80000000 0x0FFF8000> - "ddr" (code area)
>> +	<0x80000000 0x60000000> - "ddr" (data area)
>> +
>> +Note: the "ddr" code and data ranges are overlapping. Code area is smaller
>> +than data area.  So this range should be carefully chosen according to your
>> +system and application requirements.
>> +
>
> This is a source of future issues as this indicates that I should have
> reg-names list "ddr" twice.

Then I will name it:
"ddri" (incstruction/code area),
"ddrd" (data area)

unless there are other suggestions.

> Also, as you warn about the user needing to pick the values for "ddr",
> does that mean that it's a carveout of System RAM?

Yes, it is a part of System RAM.

>> +Example:
>> +	imx_rproc: imx7d-rp0@0 {
>
> imx7d-rproc@...00000 {
>
> And there's currently no reason to label this node.
>
>> +		compatible	= "fsl,imx7d-rproc";
>> +		reg		= <0x80000000 0x80000>, <0x00900000 0x2000>;
>> +		reg-names	= "ddr", "ocram";
>> +		syscon		= <&src>;
>> +		clocks		= <&clks IMX7D_ARM_M4_ROOT_CLK>;
>> +	};

Regards,
Oleksij