linux-kernel - Re: [PATCH 2/6 v5] clk, highbank: Prevent glitches in non-bypass reset mode

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Message-ID: <CAPtuhTjjTTfXRAf6BAuG0L_NQubcYwCCi6WCBYR9ddtG-koMHw@mail.gmail.com>
Date:	Tue, 27 Nov 2012 10:15:52 -0800
From:	Mike Turquette <mturquette@...aro.org>
To:	Mark Langsdorf <mark.langsdorf@...xeda.com>
Cc:	linux-kernel@...r.kernel.org, cpufreq@...r.kernel.org,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	linux-arm-kernel@...ts.infradead.org,
	Rob Herring <rob.herring@...xeda.com>
Subject: Re: [PATCH 2/6 v5] clk, highbank: Prevent glitches in non-bypass
 reset mode

On Tue, Nov 27, 2012 at 7:04 AM, Mark Langsdorf
<mark.langsdorf@...xeda.com> wrote:
>
> The highbank clock will glitch with the current code if the
> clock rate is reset without relocking the PLL. Program the PLL
> correctly to prevent glitches.
>
> Signed-off-by: Mark Langsdorf <mark.langsdorf@...xeda.com>
> Signed-off-by: Rob Herring <rob.herring@...xeda.com>
> Cc: mturquette@...aro.org

Acked-by: Mike Turquette <mturquette@...aro.org>

Regards,
Mike

> ---
> Changes from v4
>         None.
> Changes from v3
>         Changelog text and patch name now correspond to the actual patch.
>         was clk, highbank: remove non-bypass reset mode.
> Changes from v2
>         None.
> Changes from v1:
>         Removed erroneous reformating.
>
>  drivers/clk/clk-highbank.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/clk/clk-highbank.c b/drivers/clk/clk-highbank.c
> index 52fecad..3a0b723 100644
> --- a/drivers/clk/clk-highbank.c
> +++ b/drivers/clk/clk-highbank.c
> @@ -182,8 +182,10 @@ static int clk_pll_set_rate(struct clk_hw *hwclk, unsigned long rate,
>                 reg |= HB_PLL_EXT_ENA;
>                 reg &= ~HB_PLL_EXT_BYPASS;
>         } else {
> +               writel(reg | HB_PLL_EXT_BYPASS, hbclk->reg);
>                 reg &= ~HB_PLL_DIVQ_MASK;
>                 reg |= divq << HB_PLL_DIVQ_SHIFT;
> +               writel(reg | HB_PLL_EXT_BYPASS, hbclk->reg);
>         }
>         writel(reg, hbclk->reg);
>
> --
> 1.7.11.7
>
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