The Linux AMBA framework probes the peripheral ids when adding the amba
devices very early on the boot. Generally they are on APB bus and just
require APB clocks to be on even when most of the core logic of the IP
is powered down.
However on Juno, the entire debugsys domain needs to be ON to access
those CID/PID registers and hence broken by design. Accessing those
while debugsys power domain is off will lead to the bridge stalling the
transactions instead of returning the slave error.
Since keeping the power domain on by default affects the core power(by
preventing cores entering deeper idle states), it's not feasible
solution. Instead we can provide arm,primecell-periphid override in the
device tree that prevents accessing the device early in the boot.
However the power domains can be enabled whenever required using runtime
PM and associated power domains.
Cc: Liviu Dudau <liviu.dudau@xxxxxxx>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: devicetree@xxxxxxxxxxxxxxx
Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
---
arch/arm64/boot/dts/arm/juno-base.dtsi | 13 +++++++++++++
arch/arm64/boot/dts/arm/juno-r1.dts | 6 ++++++
arch/arm64/boot/dts/arm/juno-r2.dts | 6 ++++++
arch/arm64/boot/dts/arm/juno.dts | 6 ++++++
4 files changed, 31 insertions(+)
diff --git a/arch/arm64/boot/dts/arm/juno-base.dtsi b/arch/arm64/boot/dts/arm/juno-base.dtsi
index 90a8710f7032..49fa55cdc977 100644
--- a/arch/arm64/boot/dts/arm/juno-base.dtsi
+++ b/arch/arm64/boot/dts/arm/juno-base.dtsi
@@ -63,6 +63,14 @@
*/
etf@20010000 {
compatible = "arm,coresight-tmc", "arm,primecell";
+ /*
+ * The primecell peripheral id is explicitly specified here with
+ * the actual hardware value. It's not any override. It's
+ * required to workaround an errata to avoid bus stalls early
+ * in the boot when AMBA primecell ids are probed before the
+ * actual power domain can be enabled using SCPI.
+ */
+ arm,primecell-periphid = <0x001bb961>;
reg = <0 0x20010000 0 0x1000>;
clocks = <&soc_smc50mhz>;
@@ -92,6 +100,7 @@
tpiu@20030000 {
compatible = "arm,coresight-tpiu", "arm,primecell";
+ arm,primecell-periphid = <0x004bb912>;
reg = <0 0x20030000 0 0x1000>;
clocks = <&soc_smc50mhz>;
@@ -106,6 +115,7 @@
main_funnel@20040000 {
compatible = "arm,coresight-funnel", "arm,primecell";
+ arm,primecell-periphid = <0x002bb908>;
reg = <0 0x20040000 0 0x1000>;
clocks = <&soc_smc50mhz>;
@@ -142,6 +152,7 @@
etr@20070000 {
compatible = "arm,coresight-tmc", "arm,primecell";
+ arm,primecell-periphid = <0x001bb961>;
reg = <0 0x20070000 0 0x1000>;
clocks = <&soc_smc50mhz>;
@@ -192,6 +203,7 @@
cluster0_funnel@220c0000 {
compatible = "arm,coresight-funnel", "arm,primecell";
+ arm,primecell-periphid = <0x002bb908>;
reg = <0 0x220c0000 0 0x1000>;
clocks = <&soc_smc50mhz>;
@@ -227,6 +239,7 @@
cluster1_funnel@230c0000 {
compatible = "arm,coresight-funnel", "arm,primecell";
+ arm,primecell-periphid = <0x002bb908>;
reg = <0 0x230c0000 0 0x1000>;
clocks = <&soc_smc50mhz>;
diff --git a/arch/arm64/boot/dts/arm/juno-r1.dts b/arch/arm64/boot/dts/arm/juno-r1.dts
index f4f8f54f8b85..c3c9fdff49bf 100644
--- a/arch/arm64/boot/dts/arm/juno-r1.dts
+++ b/arch/arm64/boot/dts/arm/juno-r1.dts
@@ -184,24 +184,30 @@
&etm0 {
cpu = <&A57_0>;
+ arm,primecell-periphid = <0x002bb95e>;
};
&etm1 {
cpu = <&A57_1>;
+ arm,primecell-periphid = <0x002bb95e>;
};
&etm2 {
cpu = <&A53_0>;
+ arm,primecell-periphid = <0x003bb95d>;
};
&etm3 {
cpu = <&A53_1>;
+ arm,primecell-periphid = <0x003bb95d>;
};
&etm4 {
cpu = <&A53_2>;
+ arm,primecell-periphid = <0x003bb95d>;
};
&etm5 {
cpu = <&A53_3>;
+ arm,primecell-periphid = <0x003bb95d>;
};
diff --git a/arch/arm64/boot/dts/arm/juno-r2.dts b/arch/arm64/boot/dts/arm/juno-r2.dts
index d903e545b64c..c672c978f89d 100644
--- a/arch/arm64/boot/dts/arm/juno-r2.dts
+++ b/arch/arm64/boot/dts/arm/juno-r2.dts
@@ -184,24 +184,30 @@
&etm0 {
cpu = <&A72_0>;
+ arm,primecell-periphid = <0x000bb95a>;
};
&etm1 {
cpu = <&A72_1>;
+ arm,primecell-periphid = <0x000bb95a>;
};
&etm2 {
cpu = <&A53_0>;
+ arm,primecell-periphid = <0x003bb95d>;
};
&etm3 {
cpu = <&A53_1>;
+ arm,primecell-periphid = <0x003bb95d>;
};
&etm4 {
cpu = <&A53_2>;
+ arm,primecell-periphid = <0x003bb95d>;
};
&etm5 {
cpu = <&A53_3>;
+ arm,primecell-periphid = <0x003bb95d>;
};
diff --git a/arch/arm64/boot/dts/arm/juno.dts b/arch/arm64/boot/dts/arm/juno.dts
index a7270eff6939..0528e47e66d1 100644
--- a/arch/arm64/boot/dts/arm/juno.dts
+++ b/arch/arm64/boot/dts/arm/juno.dts
@@ -176,24 +176,30 @@
&etm0 {
cpu = <&A57_0>;
+ arm,primecell-periphid = <0x000bb95e>;
};
&etm1 {
cpu = <&A57_1>;
+ arm,primecell-periphid = <0x000bb95e>;
};
&etm2 {
cpu = <&A53_0>;
+ arm,primecell-periphid = <0x000bb95d>;
};
&etm3 {
cpu = <&A53_1>;
+ arm,primecell-periphid = <0x000bb95d>;
};
&etm4 {
cpu = <&A53_2>;
+ arm,primecell-periphid = <0x000bb95d>;
};
&etm5 {
cpu = <&A53_3>;
+ arm,primecell-periphid = <0x000bb95d>;
};
--
2.7.4
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