linux-kernel - [PATCH] ARM: dts: imx6sx-sdb: Remove cpufreq OPP override

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Date:   Tue, 25 Apr 2017 19:57:59 +0300
From:   Leonard Crestez <leonard.crestez@....com>
To:     Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>
CC:     Leonard Crestez <leonard.crestez@....com>,
        Fabio Estevam <fabio.estevam@....com>,
        Anson Huang <Anson.Huang@....com>,
        Peter Chen <Peter.Chen@....com>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-pm@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] ARM: dts: imx6sx-sdb: Remove cpufreq OPP override

The board file for imx6sx-dbg overrides cpufreq operating points to use
higher voltages. This is done because the board has a shared rail for
VDD_ARM_IN and VDD_SOC_IN and when using LDO bypass the shared voltage
needs to be a value suitable for both ARM and SOC.

This was introduced in:

commit 54183bd7f766 ("ARM: imx6sx-sdb: add revb board and make it default")

This only only applies to LDO bypass mode, a feature not present in
upstream. When LDOs are enabled the effect is to use higher voltages than
necesarry for no good reason.

Setting these higher voltages can make some boards fail to boot with ugly
semi-random crashes, reminiscent of memory corruption. These failures
happen the first time the lowest idle state is used. Remove the OPP
override in order to fix those crashes.

Signed-off-by: Leonard Crestez <leonard.crestez@....com>

---
It's not clear exactly why the crashes happen. Perhaps waking up from idle
draws more power than is available? Removing this override is a correct
change anyway so maybe there is no need to investigate deeper.

 arch/arm/boot/dts/imx6sx-sdb.dts | 17 -----------------
 1 file changed, 17 deletions(-)

diff --git a/arch/arm/boot/dts/imx6sx-sdb.dts b/arch/arm/boot/dts/imx6sx-sdb.dts
index 5bb8fd5..d71da30 100644
--- a/arch/arm/boot/dts/imx6sx-sdb.dts
+++ b/arch/arm/boot/dts/imx6sx-sdb.dts
@@ -12,23 +12,6 @@
 	model = "Freescale i.MX6 SoloX SDB RevB Board";
 };
 
-&cpu0 {
-	operating-points = <
-		/* kHz    uV */
-		996000  1250000
-		792000  1175000
-		396000  1175000
-		198000  1175000
-		>;
-	fsl,soc-operating-points = <
-		/* ARM kHz      SOC uV */
-		996000	1250000
-		792000	1175000
-		396000	1175000
-		198000  1175000
-	>;
-};
-
 &i2c1 {
 	clock-frequency = <100000>;
 	pinctrl-names = "default";
-- 
2.7.4