linux-kernel - Re: [PATCH v5 2/3] clk: meson: add DT documentation for emmc clock controller

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Date:   Wed, 24 Oct 2018 10:58:42 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Jianxin Pan <jianxin.pan@...ogic.com>,
        Neil Armstrong <narmstrong@...libre.com>
Cc:     Yixun Lan <yixun.lan@...ogic.com>,
        Kevin Hilman <khilman@...libre.com>,
        Carlo Caione <carlo@...one.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Boris Brezillon <boris.brezillon@...tlin.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        Liang Yang <liang.yang@...ogic.com>,
        Jian Hu <jian.hu@...ogic.com>,
        Qiufang Dai <qiufang.dai@...ogic.com>,
        Hanjie Lin <hanjie.lin@...ogic.com>,
        Victor Wan <victor.wan@...ogic.com>, linux-clk@...r.kernel.org,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/3] clk: meson: add DT documentation for emmc clock
 controller

On Thu, 2018-10-18 at 13:07 +0800, Jianxin Pan wrote:
> From: Yixun Lan <yixun.lan@...ogic.com>
> 
> Document the MMC sub clock controller driver, the potential consumer
> of this driver is MMC or NAND. Also add four clock bindings IDs which
> provided by this driver.
> 
> Reviewed-by: Rob Herring <robh@...nel.org>
> Signed-off-by: Yixun Lan <yixun.lan@...ogic.com>
> Signed-off-by: Jianxin Pan <jianxin.pan@...ogic.com>
> ---
>  .../devicetree/bindings/clock/amlogic,mmc-clkc.txt | 31 ++++++++++++++++++++++
>  include/dt-bindings/clock/amlogic,mmc-clkc.h       | 17 ++++++++++++
>  2 files changed, 48 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/clock/amlogic,mmc-clkc.txt
>  create mode 100644 include/dt-bindings/clock/amlogic,mmc-clkc.h
> 
> diff --git a/Documentation/devicetree/bindings/clock/amlogic,mmc-clkc.txt b/Documentation/devicetree/bindings/clock/amlogic,mmc-clkc.txt
> new file mode 100644
> index 0000000..9e6d343
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/amlogic,mmc-clkc.txt
> @@ -0,0 +1,31 @@
> +* Amlogic MMC Sub Clock Controller Driver
> +
> +The Amlogic MMC clock controller generates and supplies clock to support
> +MMC and NAND controller
> +
> +Required Properties:
> +
> +- compatible: should be:
> +		"amlogic,gx-mmc-clkc"
> +		"amlogic,axg-mmc-clkc"
> +
> +- #clock-cells: should be 1.
> +- clocks: phandles to clocks corresponding to the clock-names property
> +- clock-names: list of parent clock names
> +	- "clkin0", "clkin1"
> +
> +Parent node should have the following properties :
> +- compatible: "amlogic,axg-mmc-clkc", "syscon".
> +- reg: base address and size of the MMC control register space.

I get why Stephen is confused by your description, I am too. The example
contradict the documentation.

The  documentation above says that the parent node should be a syscon with the
mmc register space.

But your example shows this in the node itself.

> +
> +Example: Clock controller node:
> +
> +sd_mmc_c_clkc: clock-controller@...0 {
> +	compatible = "amlogic,axg-mmc-clkc", "syscon";
> +	reg = <0x0 0x7000 0x0 0x4>;
> +	#clock-cells = <1>;
> +
> +	clock-names = "clkin0", "clkin1";
> +	clocks = <&clkc CLKID_SD_MMC_C_CLK0>,
> +		 <&clkc CLKID_FCLK_DIV2>;
> +};
> diff --git a/include/dt-bindings/clock/amlogic,mmc-clkc.h b/include/dt-bindings/clock/amlogic,mmc-clkc.h
> new file mode 100644
> index 0000000..162b949
> --- /dev/null
> +++ b/include/dt-bindings/clock/amlogic,mmc-clkc.h
> @@ -0,0 +1,17 @@
> +/* SPDX-License-Identifier: (GPL-2.0+ OR MIT) */
> +/*
> + * Meson MMC sub clock tree IDs
> + *
> + * Copyright (c) 2018 Amlogic, Inc. All rights reserved.
> + * Author: Yixun Lan <yixun.lan@...ogic.com>
> + */
> +
> +#ifndef __MMC_CLKC_H
> +#define __MMC_CLKC_H
> +
> +#define CLKID_MMC_DIV				1
> +#define CLKID_MMC_PHASE_CORE			2
> +#define CLKID_MMC_PHASE_TX			3
> +#define CLKID_MMC_PHASE_RX			4
> +
> +#endif