linux-kernel - Re: [PATCH 1/9] phy: core: Change the way of_phy

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Date:	Mon, 9 Dec 2013 12:52:40 +0530
From:	Kishon Vijay Abraham I <kishon@...com>
To:	Kamil Debski <k.debski@...sung.com>
CC:	<linux-kernel@...r.kernel.org>,
	<linux-samsung-soc@...r.kernel.org>, <linux-usb@...r.kernel.org>,
	<devicetree@...r.kernel.org>, <kyungmin.park@...sung.com>,
	Tomasz Figa <t.figa@...sung.com>,
	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	<gautam.vivek@...sung.com>, <mat.krawczuk@...il.com>,
	<yulgon.kim@...sung.com>, <p.paneri@...sung.com>,
	<av.tikhomirov@...sung.com>, <jg1.han@...sung.com>,
	<galak@...eaurora.org>, <matt.porter@...aro.org>
Subject: Re: [PATCH 1/9] phy: core: Change the way of_phy_get is called

On Friday 06 December 2013 04:22 PM, Kamil Debski wrote:
> Hi,
>
>> From: Kishon Vijay Abraham I [mailto:kishon@...com]
>> Sent: Friday, December 06, 2013 6:31 AM
>>
>> Hi,
>>
>> On Thursday 05 December 2013 05:59 PM, Kamil Debski wrote:
>>> Previously the of_phy_get function took a struct device * and was
>>> declared static. It was impossible to call it from another driver and
>>> thus it was impossible to get phy defined
>>
>> It was never intended to be called from other drivers. What's up with
>> the wrapper of of_phy_get, phy_get()/devm_phy_get()? Why isn't that
>> enough?
>
> Implementing support for multiple phys in the ehci driver is a bit tricky.
> Especially when we want to do it right. Please have a look at this part of
> the dts file:
>
> +    ehci@...80000 {
> +        compatible = "samsung,exynos4210-ehci";
> +        reg = <0x12580000 0x20000>;
> +        interrupts = <0 70 0>;
> +        clocks = <&clock 304>, <&clock 305>;
> +        clock-names = "usbhost", "otg";
> +        status = "disabled";
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +        port@0 {
> +            reg = <0>;
> +            phys = <&usb2phy 1>;
> +            phy-names = "host";
> +            status = "disabled";
> +        };
> +        port@1 {
> +            reg = <1>;
> +            phys = <&usb2phy 2>;
> +            phy-names = "hsic0";
> +            status = "disabled";
> +        };
> +        port@2 {
> +            reg = <2>;
> +            phys = <&usb2phy 3>;
> +            phy-names = "hsic1";
> +            status = "disabled";
> +        };
> +    };
>
> With the above we have a clear specification of ports and their respective
> phys. But to do this properly the ehci driver has to iterate over port
> nodes. It is much easier to use devm_of_phy_get by giving the node as its
> argument.

I see. There are a couple of more things we do in the wrapper that gets 
missed while exporting of_phy_get (get_device and try_module_get). You 
might want to re-work that one.

Thanks
Kishon
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