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authorMark Brown <broonie@kernel.org>2016-01-26 21:08:06 +0300
committerMark Brown <broonie@kernel.org>2016-01-27 21:49:42 +0300
commit25d6463e48ea41149c88dc40648a888699e77158 (patch)
tree30133c23acc2da7eafede752e2d61dc6c8985398 /arch/mips/boot/dts/brcm/bcm7420.dtsi
parenta06c488da0b0c1eebf710017675f00b9d5f9cf42 (diff)
downloadlinux-25d6463e48ea41149c88dc40648a888699e77158.tar.xz
MIPS: dt: Explicitly specify native endian behaviour for syscon
On many MIPS systems the endianness of IP blocks is kept the same as that of the CPU by the hardware. This includes the system controllers on these systems which are controlled via syscon which uses the regmap API which used readl() and writel() to interact with the hardware, meaning that all writes are converted to little endian when writing to the hardware. This caused a bad interaction with the regmap core in big endian mode since it was not aware of the byte swapping and so ended up performing little endian writes. Unfortunately when this issue was noticed it was addressed by updating the DT for the affected devices to specify them as little endian. This happened to work since it resulted in two endianness swaps which cancelled each other out and gave little endian behaviour but meant that the DT was clearly not accurately describing the hardware. The intention of commit 29bb45f25ff305 (regmap-mmio: Use native endianness for read/write) was to fix this by making regmap default to native endianness but this breaks most other MMIO users where the hardware has a fixed endianness and the implementation uses the __raw accessors which are not intended to be used outside of architecture code. Instead use the newly added native-endian DT property to say exactly what we want for these systems. Fixes: 29bb45f25ff305 (regmap-mmio: Use native endianness for read/write) Reported-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: Mark Brown <broonie@kernel.org> Acked-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/boot/dts/brcm/bcm7420.dtsi')
-rw-r--r--arch/mips/boot/dts/brcm/bcm7420.dtsi1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/mips/boot/dts/brcm/bcm7420.dtsi b/arch/mips/boot/dts/brcm/bcm7420.dtsi
index bee221b3b568..3302a1b8a5c9 100644
--- a/arch/mips/boot/dts/brcm/bcm7420.dtsi
+++ b/arch/mips/boot/dts/brcm/bcm7420.dtsi
@@ -99,6 +99,7 @@
sun_top_ctrl: syscon@404000 {
compatible = "brcm,bcm7420-sun-top-ctrl", "syscon";
reg = <0x404000 0x60c>;
+ native-endian;
};
reboot {