linux-kernel - Re: [PATCH 0/4] clk: mvebu: fix clk init order

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Message-ID: <52E43046.1030105@gmail.com>
Date:	Sat, 25 Jan 2014 22:44:38 +0100
From:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
To:	Emilio López <emilio@...pez.com.ar>
CC:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>,
	Andrew Lunn <andrew@...n.ch>,
	Mike Turquette <mturquette@...aro.org>,
	Jason Cooper <jason@...edaemon.net>,
	linux-kernel@...r.kernel.org,
	Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>,
	Gregory Clement <gregory.clement@...e-electrons.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 0/4] clk: mvebu: fix clk init order

On 01/25/2014 10:32 PM, Emilio López wrote:
> El 25/01/14 15:19, Sebastian Hesselbarth escribió:
>> This patch set fixes clk init order that went upside-down with
>> v3.14. I haven't really investigated what caused this, but I assume
>> it is related with DT node reordering by addresses.
>
> The framework should be able to deal with unordered registration. I am
> not very familiar with the mvebu driver though, do you have a valid
> reason to require a specific order?

Emilio,

I rather think that everthing registered with CLK_OF_DECLARE cannot
deal with unordered registration. The callback passed to CLK_OF_DECLARE
has to have void as return value, so there is no way to pass errors,
e.g. -EPROBE_DEFER, back to of_clk_init.

The reason for this ordering is that the clock gates depend on core
clocks. It is always that way, so merging both init functions isn't
that odd.

>> Anyway, with v3.14 for MVEBU SoCs, the clock gating driver gets
>> registered before core clocks driver. Unfortunately, we cannot
>> return -EPROBE_DEFER in drivers initialized by clk_of_init.
>
> Why would you need to do so? After a quick inspection on the code, I see
> you may have problems on mvebu_clk_gating_setup() when getting the
> default parent clock name, but I believe you could solve it in an easier
> way by using of_clk_get_parent_name().

Ok, I'll look if using of_clk_get_parent_name will help here. But again,
I can see that clk-gating driver gets registered before core-clk driver.
There may be no code to give you the parent name at that time.

Sebastian

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