From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <jszhang@marvell.com>
Date: Wed, 9 Mar 2016 15:24:20 +0800
From: Jisheng Zhang <jszhang@marvell.com>
To: Stephen Boyd <sboyd@codeaurora.org>,
        Michael Turquette
	<mturquette@baylibre.com>,
        <linux-clk@vger.kernel.org>, <linux-arm-kernel@lists.infradead.org>,
        Sebastian Hesselbarth
	<sebastian.hesselbarth@gmail.com>
Subject: [Query]set clk rate must operate its coordinated clock
Message-ID: <20160309152420.20de187a@xhacker>
MIME-Version: 1.0
Content-Type: text/plain; charset="US-ASCII"
List-ID: <linux-clk.vger.kernel.org>

Dear Stephen, Michael, Sebastian and all, 

I have the following clk case which I dunno the elegant solution:


cpuclk have two parents: cpupll and refclk. When set the cpuclk freq, we
have to set its parent's freq, I.E cpupll freq. But before changing the
cpupll's freq, we should set its refclk as its parent firstly.

AFAIK, this is a common case, I have seen such requirement in rockchip, samsung
clk driver. They solve this by notifier, but as pointed out by Michael
in http://lists.infradead.org/pipermail/linux-arm-kernel/2015-June/351565.html

"This is also a hack and it points towards some missing infrastructure in the
clock framework."

I also don't like the notifier solution, I believe the elegant solution could
be using the coordinated clock infrastructure. So what's the status of
this infrastructure? I can test, and I can even add some code to make it be
ready to be merged if you guide me ;)

Thanks in advance,
Jisheng