linux-kernel - Re: [LINUX PATCH v9 1/4] Devicetree: Add pl353 smc controller devicetree binding information

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Message-ID: <20180607174203.035f187d@xps13>
Date:   Thu, 7 Jun 2018 17:42:03 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Naga Sureshkumar Relli <naga.sureshkumar.relli@...inx.com>
Cc:     <boris.brezillon@...tlin.com>, <richard@....at>,
        <wmw2@...radead.org>, <computersforpeace@...il.com>,
        <marek.vasut@...il.com>, <f.fainelli@...il.com>,
        <mmayer@...adcom.com>, <rogerq@...com>, <ladis@...ux-mips.org>,
        <ada@...rsis.com>, <honghui.zhang@...iatek.com>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <nagasureshkumarrelli@...il.com>
Subject: Re: [LINUX PATCH v9 1/4] Devicetree: Add pl353 smc controller
 devicetree binding information

Hi Naga,

On Wed, 6 Jun 2018 13:19:39 +0530, Naga Sureshkumar Relli
<naga.sureshkumar.relli@...inx.com> wrote:

> Add pl353 static memory controller devicetree binding information.
> 
> Signed-off-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@...inx.com>
> ---
> Changes in v9:
>  - Addressed commens given by Randy Dunlap and Miquel Raynal

Can you please be more specific in your next changelog? I don't
remember what I suggested a few months ago :)

> Changes in v8:
>  - None
> Changes in v7:
> - Corrected clocks description
> - prefixed '#' for address and size cells 
> Changes in v6:
>  - None
> Changes in v5:
>  - Removed timing properties
> Changes in v4:
>  - none
> Changes in v3:
>  - none
> Changes in v2:
>  - modified timing binding info as per onfi timing parameters
>  - add suffix nano second as timing unit
>  - modified the clock names as per the IP spec
> ---
>  .../bindings/memory-controllers/pl353-smc.txt      | 53 ++++++++++++++++++++++
>  1 file changed, 53 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/memory-controllers/pl353-smc.txt
> 
> diff --git a/Documentation/devicetree/bindings/memory-controllers/pl353-smc.txt b/Documentation/devicetree/bindings/memory-controllers/pl353-smc.txt
> new file mode 100644
> index 0000000..551e66b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/memory-controllers/pl353-smc.txt
> @@ -0,0 +1,53 @@
> +Device tree bindings for ARM PL353 static memory controller
> +
> +PL353 static memory controller supports two kinds of memory
> +interfaces.i.e NAND and SRAM/NOR interfaces.
> +The actual devices are instantiated from the child nodes of pl353 smc node.
> +
> +Required properties:
> +- compatible		: Should be "arm,pl353-smc-r2p1"

I thing Rob prefers:

- compatible: Must be one of:
  * arm, pl353-smc-r2p1

> +- reg			: Controller registers map and length.
> +- clock-names		: List of input clock names - "ref_clk", "aper_clk"
> +			  (See clock bindings for details).
> +- clocks		: Clock phandles (see clock bindings for details).
> +- address-cells		: Address cells, must be 1.
> +- size-cells		: Size cells. Must be 1.

Please avoid padding, just this is enough:

- something: And another thing.

> +
> +Child nodes:
> + For NAND the "arm,pl353-nand-r2p1" and for NOR the "cfi-flash" drivers are
> +supported as child nodes.
> +
> +Mandatory timing properties for child nodes:
> +- arm,nand-cycle-t0	: Read cycle time(t_rc).
> +- arm,nand-cycle-t1	: Write cycle time(t_wc).
> +- arm,nand-cycle-t2	: re_n assertion delay(t_rea).
> +- arm,nand-cycle-t3	: we_n de-assertion delay(t_wp).
> +- arm,nand-cycle-t4	: Status read time(t_clr)
> +- arm,nand-cycle-t5	: ID read time(t_ar)
> +- arm,nand-cycle-t6	: busy to re_n(t_rr)

I think this has nothing to do in the DT, you should handle timings
from the ->setup_data_interface() hook. If you need, you may use
different compatibles to distinguish different platform data.

> +
> +for nand partition information please refer the below file

s/nand/NAND/

> +Documentation/devicetree/bindings/mtd/partition.txt
> +
> +Example:
> +	pl353smcc_0: pl353smcc@...0e000 {

Why not something more explicit with the '-flash-controller' suffix?

> +			compatible = "arm,pl353-smc-r2p1"
> +			clock-names = "memclk", "aclk";
> +			clocks = <&clkc 11>, <&clkc 44>;
> +			reg = <0xe000e000 0x1000>;
> +			#address-cells = <1>;
> +			#size-cells = <1>;
> +			ranges;
> +			nand_0: nand@...00000 {
> +				compatible = "arm,pl353-nand-r2p1"

NAND chips do not have their own compatible.

> +				reg = <0xe1000000 0x1000000>;
> +				arm,nand-cycle-t0 = <0x4>;
> +				arm,nand-cycle-t1 = <0x4>;
> +				arm,nand-cycle-t2 = <0x1>;
> +				arm,nand-cycle-t3 = <0x2>;
> +				arm,nand-cycle-t4 = <0x2>;
> +				arm,nand-cycle-t5 = <0x2>;
> +				arm,nand-cycle-t6 = <0x4>;
> +				(...)
> +			};
> +	};


Thanks,
Miquèl