Date: Thu, 17 Mar 2016 10:01:40 -0500
From: Rob Herring <robh@kernel.org>
To: Franklin S Cooper Jr <fcooper@ti.com>
Cc: thierry.reding@gmail.com, pawel.moll@arm.com, mark.rutland@arm.com,
        ijc+devicetree@hellion.org.uk, galak@codeaurora.org,
        bcousson@baylibre.com, tony@atomide.com, linux@arm.linux.org.uk,
        t-kristo@ti.com, mturquette@baylibre.com, sboyd@codeaurora.org,
        linux-pwm@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-clk@vger.kernel.org
Subject: Re: [PATCH 4/5] pwm: pwm-tipwmss: Update documentation to use empty
 range property
Message-ID: <20160317150140.GA25775@rob-hp-laptop>
References: <1457380318-15452-1-git-send-email-fcooper@ti.com>
 <1457380318-15452-5-git-send-email-fcooper@ti.com>
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On Mon, Mar 07, 2016 at 01:51:57PM -0600, Franklin S Cooper Jr wrote:
> Since the PWMSS and its subdevices (eCAP and ePWM) use the same address
> space then the range property should be empty. Update the documentation
> to show the correct usage.

Why does it matter? An empty ranges is generally not preferred.

> 
> Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
> ---
>  Documentation/devicetree/bindings/pwm/pwm-tipwmss.txt | 12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/pwm/pwm-tipwmss.txt b/Documentation/devicetree/bindings/pwm/pwm-tipwmss.txt
> index f7eae77..672fa71 100644
> --- a/Documentation/devicetree/bindings/pwm/pwm-tipwmss.txt
> +++ b/Documentation/devicetree/bindings/pwm/pwm-tipwmss.txt
> @@ -7,11 +7,9 @@ Required properties:
>  		  Should set to 1.
>  - size-cells: specify number of u32 entries needed to specify child nodes size
>  		in reg property. Should set to 1.
> -- ranges: describes the address mapping of a memory-mapped bus. Should set to
> -	   physical address map of child's base address, physical address within
> -	   parent's address  space and length of the address map. For am33xx,
> -	   3 set of child register maps present, ECAP register space, EQEP
> -	   register space, EHRPWM register space.
> +- ranges: describes the address mapping of a memory-mapped bus. Its value
> +	  should be empty since no address translation is needed between the
> +	  parent and the child.
>  
>  Also child nodes should also populated under PWMSS DT node.
>  
> @@ -23,9 +21,7 @@ pwmss0: pwmss@48300000 {
>  	#address-cells = <1>;
>  	#size-cells = <1>;
>  	status = "disabled";
> -	ranges = <0x48300100 0x48300100 0x80   /* ECAP */
> -		  0x48300180 0x48300180 0x80   /* EQEP */
> -		  0x48300200 0x48300200 0x80>; /* EHRPWM */
> +	ranges;
>  
>  	/* child nodes go here */
>  };
> -- 
> 2.7.0
>