linux-kernel - [PATCH] ARM: dts: Switch i2c0 to 400kHz on rk3288-evb-rk808

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Date:	Wed, 10 Sep 2014 21:30:15 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	Heiko Stuebner <heiko@...ech.de>
Cc:	Chris Zhong <zyw@...k-chips.com>, Addy Ke <addy.ke@...k-chips.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org,
	Doug Anderson <dianders@...omium.org>, robh+dt@...nel.org,
	pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	linux@....linux.org.uk, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] ARM: dts: Switch i2c0 to 400kHz on rk3288-evb-rk808

We should be able to talk to the PMIC at 400kHz.  No need to talk at
the slow 100kHz.

As measured by ftrace (with a bunch of extra patches, since cpufreq
for rk808 hasn't landed yet):
  before this change: cpu0_set_target() => ~500us
  after this change:  cpu0_set_target() => ~300us

Signed-off-by: Doug Anderson <dianders@...omium.org>
---
 arch/arm/boot/dts/rk3288-evb-rk808.dts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/boot/dts/rk3288-evb-rk808.dts b/arch/arm/boot/dts/rk3288-evb-rk808.dts
index 36db177..ff522f8 100644
--- a/arch/arm/boot/dts/rk3288-evb-rk808.dts
+++ b/arch/arm/boot/dts/rk3288-evb-rk808.dts
@@ -18,6 +18,7 @@
 };
 
 &i2c0 {
+	clock-frequency = <400000>;
 	status = "okay";
 
 	rk808: pmic@1b {
-- 
2.1.0.rc2.206.gedb03e5

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