netdev - Re: [PATCH] net: phy: micrel: support !CONFIG_HAVE

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Date:	Mon, 4 May 2015 13:30:58 +0200
From:	Niklas Cassel <niklas.cassel@...s.com>
To:	Fabio Estevam <festevam@...il.com>
CC:	"David S. Miller" <davem@...emloft.net>,
	Florian Fainelli <f.fainelli@...il.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"johan@...nel.org" <johan@...nel.org>
Subject: Re: [PATCH] net: phy: micrel: support !CONFIG_HAVE_CLK

On 04/27/2015 07:59 PM, Fabio Estevam wrote:
> On Mon, Apr 27, 2015 at 8:00 AM, Niklas Cassel <niklas.cassel@...s.com> wrote:
> 
>> Since NULL is a valid clock, we shouldn't use
>> IS_ERR_OR_NULL.
> 
> Yes, but this code is not using IS_ERR_OR_NULL.
> 
> It seems that you are not describing the problem you are trying to solve.
> 
> What is the exact issue you are seeing?
> 
>>         clk = devm_clk_get(&phydev->dev, "rmii-ref");
> 
> You need to provide the 'rmii-ref' in your board file or dts.
> 
> Are you doing this?
> 

I'm sorry, my commit message didn't really describe the problem properly.

When you compile your kernel without the clk.h API (CONFIG_HAVE_CLK),
devm_clk_get returns NULL (which also happens to be a valid clock in the clk.h API).
So it's not a matter of DT or board-files. This is on a mips platform without DT support.

I simply want the drivers/net/phy/micrel.c driver to also work without CONFIG_HAVE_CLK,
like it did before commit

63f44b2bfccdd98193bbd602747f780c0fae0f02
net: phy: micrel: add generic clock-mode-select support

Now I get an error every time I boot with "Clock rate out of range: 0",
since clk_get_rate returns 0 when compiling with !CONFIG_HAVE_CLK.

It is confusing that devm_clk_get returns a valid clock in the clk.h API (NULL),
when compiling with !CONFIG_HAVE_CLK, but according to Russell King in:

http://lkml.kernel.org/r/20150207172949.GE8656@n2100.arm.linux.org.uk

this was intentional. (explained in the lkml mail above.)

In the same mail Russell King also suggests how a driver can support both
!CONFIG_HAVE_CLK and CONFIG_HAVE_CLK.

This is the suggestion I followed when writing my patch.
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