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

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Message-ID: <20150526074608.GE6325@pengutronix.de>
Date:	Tue, 26 May 2015 09:46:08 +0200
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	James Liao <jamesjj.liao@...iatek.com>
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 Thu, May 21, 2015 at 03:12:53PM +0800, James Liao wrote:
> From: Sascha Hauer <s.hauer@...gutronix.de>
> 
> On the MT8173 the clocks are provided by different units. To enable
> the critical clocks we must be sure that all parent clocks are already
> registered, otherwise the parents of the critical clocks end up being
> unused and get disabled later. To find a place where all parents are
> registered we try each time after we've registered some clocks if
> all known providers are present now and only then we enable the critical
> clocks
> 
> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> Signed-off-by: James Liao <jamesjj.liao@...iatek.com>
> ---
>  drivers/clk/mediatek/clk-mt8173.c | 24 +++++++++++++++++++-----
>  1 file changed, 19 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/clk/mediatek/clk-mt8173.c b/drivers/clk/mediatek/clk-mt8173.c
> index 4b9e04c..eb175ac 100644
> --- a/drivers/clk/mediatek/clk-mt8173.c
> +++ b/drivers/clk/mediatek/clk-mt8173.c
> @@ -700,6 +700,20 @@ static const struct mtk_composite peri_clks[] __initconst = {
>  	MUX(CLK_PERI_UART3_SEL, "uart3_ck_sel", uart_ck_sel_parents, 0x40c, 3, 1),
>  };
>  
> +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?

Sascha


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