linux-kernel - Re: [PATCH 2/5] clk: mediatek: mt8173: Fix enabling of critical clocks

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Date:	Tue, 26 May 2015 16:36:03 +0800
From:	James Liao <jamesjj.liao@...iatek.com>
To:	Sascha Hauer <s.hauer@...gutronix.de>
CC:	Matthias Brugger <matthias.bgg@...il.com>,
	Mike Turquette <mturquette@...aro.org>,
	Stephen Boyd <sboyd@...eaurora.org>,
	<srv_heupstream@...iatek.com>,
	Eddie Huang <eddie.huang@...iatek.com>,
	"Henry Chen" <henryc.chen@...iatek.com>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Daniel Kurtz <djkurtz@...omium.org>,
	Ricky Liang <jcliang@...omium.org>,
	Rob Herring <robh+dt@...nel.org>,
	Sascha Hauer <kernel@...gutronix.de>,
	<devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH 2/5] clk: mediatek: mt8173: Fix enabling of critical
 clocks

On Tue, 2015-05-26 at 09:46 +0200, Sascha Hauer wrote:
> > +static struct clk_onecell_data *mt8173_top_clk_data;
> > +static struct clk_onecell_data *mt8173_pll_clk_data;
> > +
> > +static void mtk_clk_enable_critical(void)
> > +{
> > +	if (!mt8173_top_clk_data || !mt8173_pll_clk_data)
> > +		return;
> > +
> > +	clk_prepare_enable(mt8173_top_clk_data->clks[CLK_TOP_MEM_SEL]);
> > +	clk_prepare_enable(mt8173_top_clk_data->clks[CLK_TOP_DDRPHYCFG_SEL]);
> > +	clk_prepare_enable(mt8173_top_clk_data->clks[CLK_TOP_CCI400_SEL]);
> > +	clk_prepare_enable(mt8173_top_clk_data->clks[CLK_TOP_RTC_SEL]);
> 
> Is CLK_TOP_RTC_SEL really a critical clock?

CLK_TOP_RTC_SEL is the main 32k clock used by some system hardware such
sleep controller on MT8173. This clock should not be turned off even
when software/CPU is sleeping. So it's a better way to set
CLK_TOP_RTC_SEL as a critical clock (an always on clock).


Best regards,

James

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