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authorStefan Agner <stefan@agner.ch>2015-11-30 17:59:26 -0800
committerShawn Guo <shawnguo@kernel.org>2015-12-11 21:32:47 +0800
commit9c17190595840b4ed30e8d5f286636ceb28aae4f (patch)
treec44a2146712740b7a76a27df89be93f2b49af41c
parent531ee1f4ea7fb5634cb79824e6df6be83596a054 (diff)
downloadlinux-linaro-stable-9c17190595840b4ed30e8d5f286636ceb28aae4f.tar.gz
ARM: dts: vf610: use reset values for L2 cache latencies
Linux on Vybrid used several different L2 latencies so far, none of them seem to be the right ones. According to the application note AN4947 ("Understanding Vybrid Architecture"), the tag portion runs on CPU clock and is inside the L2 cache controller, whereas the data portion is stored in the external SRAM running on platform clock. Hence it is likely that the correct value requires a higher data latency then tag latency. These are the values which have been used so far: - The mainline values: arm,data-latency = <1 1 1>; arm,tag-latency = <2 2 2>; Those values have lead to problems on higher clocks. They look like a poor translation from the reset values (missing +1 offset and a mix up between tag/latency values). - The Linux 3.0 (SoC vendor BSP) values (converted to DT notation): arm,data-latency = <4 2 3> arm,tag-latency = <4 2 3> The cache initialization function along with the value matches the i.MX6 code from the same kernel, so it seems that those values have just been copied. - The Colibri values: arm,data-latency = <2 1 2>; arm,tag-latency = <3 2 3>; Those were a mix between the values of the Linux 3.0 based BSP and the mainline values above. - The SoC Reset values (converted to DT notation): arm,data-latency = <3 3 3>; arm,tag-latency = <2 2 2>; So far there is no official statement on what the correct values are. See also the related Freescale community thread: https://community.freescale.com/message/579785#579785 For now, the reset values seem to be the best bet. Remove all other "bogus" values and use the reset value on vf610.dtsi level. Signed-off-by: Stefan Agner <stefan@agner.ch> Cc: <stable@vger.kernel.org> Signed-off-by: Shawn Guo <shawnguo@kernel.org>
-rw-r--r--arch/arm/boot/dts/vf610-colibri.dtsi5
-rw-r--r--arch/arm/boot/dts/vf610.dtsi2
2 files changed, 1 insertions, 6 deletions
diff --git a/arch/arm/boot/dts/vf610-colibri.dtsi b/arch/arm/boot/dts/vf610-colibri.dtsi
index 19fe045b8334..2d7eab755210 100644
--- a/arch/arm/boot/dts/vf610-colibri.dtsi
+++ b/arch/arm/boot/dts/vf610-colibri.dtsi
@@ -18,8 +18,3 @@
reg = <0x80000000 0x10000000>;
};
};
-
-&L2 {
- arm,data-latency = <2 1 2>;
- arm,tag-latency = <3 2 3>;
-};
diff --git a/arch/arm/boot/dts/vf610.dtsi b/arch/arm/boot/dts/vf610.dtsi
index 5f8eb1bd782b..58bc6e448be5 100644
--- a/arch/arm/boot/dts/vf610.dtsi
+++ b/arch/arm/boot/dts/vf610.dtsi
@@ -19,7 +19,7 @@
reg = <0x40006000 0x1000>;
cache-unified;
cache-level = <2>;
- arm,data-latency = <1 1 1>;
+ arm,data-latency = <3 3 3>;
arm,tag-latency = <2 2 2>;
};
};