From: Maxime Ripard <maxime.ripard@free-electrons.com>
To: Chen-Yu Tsai <wens@csie.org>
Cc: Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@codeaurora.org>,
linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
Subject: Re: [PATCH v3 4/6] clk: sunxi-ng: mux: Add clk notifier functions
Date: Thu, 25 Aug 2016 22:31:17 +0200 [thread overview]
Message-ID: <20160825203117.GE32598@lukather> (raw)
In-Reply-To: <20160825062200.17206-5-wens@csie.org>
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On Thu, Aug 25, 2016 at 02:21:58PM +0800, Chen-Yu Tsai wrote:
> On sunxi we support cpufreq by changing the clock rate of PLL-CPU.
> It's possible the clock output of the PLL goes out of the CPU's
> operational limits when the PLL's multipliers / dividers are changed
> and it hasn't stabilized yet. This would result in the CPU hanging.
>
> To circumvent this, we temporarily switch the CPU mux clock to another
> stable clock before the rate change, and switch it back after the PLL
> stabilizes. This is done with clk notifiers registered on the PLL.
>
> This patch adds common functions for notifiers to reparent mux clocks.
>
> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Applied, thanks!
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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next prev parent reply other threads:[~2016-08-25 20:31 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-25 6:21 [PATCH v3 0/6] clk: sunxi-ng: Support A31/A31s CCU Chen-Yu Tsai
2016-08-25 6:21 ` [PATCH v3 1/6] clk: sunxi-ng: nkm: Correct mux clock macro name Chen-Yu Tsai
2016-08-25 20:26 ` Maxime Ripard
2016-08-25 6:21 ` [PATCH v3 2/6] clk: sunxi-ng: mux: Add support for mux tables Chen-Yu Tsai
2016-08-25 20:27 ` Maxime Ripard
2016-08-25 6:21 ` [PATCH v3 3/6] clk: sunxi-ng: mux: support fixed pre-dividers on multiple parents Chen-Yu Tsai
[not found] ` <20160825062200.17206-4-wens-jdAy2FN1RRM@public.gmane.org>
2016-08-25 20:27 ` Maxime Ripard
2016-08-25 6:21 ` [PATCH v3 4/6] clk: sunxi-ng: mux: Add clk notifier functions Chen-Yu Tsai
2016-08-25 20:31 ` Maxime Ripard [this message]
[not found] ` <20160825062200.17206-1-wens-jdAy2FN1RRM@public.gmane.org>
2016-08-25 6:21 ` [PATCH v3 5/6] clk: sunxi-ng: Add A31/A31s clocks Chen-Yu Tsai
2016-08-25 20:31 ` Maxime Ripard
2016-08-25 6:22 ` [PATCH v3 6/6] ARM: dts: sun6i: switch A31/A31s to new CCU clock bindings Chen-Yu Tsai
2016-08-25 20:32 ` Maxime Ripard
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