Re: [PATCH 2/2] arm: dts: mt6589: Add device tree for Fairphone 1
From: Matthias Brugger
Date: Wed Oct 13 2021 - 12:20:48 EST
On 12/10/2021 19:54, Luca Weiss wrote:
Hi Matthias,
On Freitag, 8. Oktober 2021 13:49:25 CEST Matthias Brugger wrote:
On 05/10/2021 22:28, Luca Weiss wrote:
Add rudimentary support for the Fairphone 1, based on MT6589 to boot to
UART console.
The recently added SMP support needs to be disabled for this board as
the kernel panics executing /init with it, even though the CPUs seem to
start up fine - maybe a stability issue.
[ 0.072010] smp: Bringing up secondary CPUs ...
[ 0.131888] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
[ 0.191889] CPU2: thread -1, cpu 2, socket 0, mpidr 80000002
[ 0.251890] CPU3: thread -1, cpu 3, socket 0, mpidr 80000003
[ 0.251982] smp: Brought up 1 node, 4 CPUs
[ 0.254745] SMP: Total of 4 processors activated (7982.28 BogoMIPS).
[ 0.255582] CPU: All CPU(s) started in SVC mode.
[ 0.472039] Run /init as init process
[ 0.473317] Kernel panic - not syncing: Attempted to kill init!
exitcode=0x00000004
Would be nice to find out why. Did you tried to boot the system with
enable-method set but with bringing up just one or two cpus?
Answered further down.
Signed-off-by: Luca Weiss <luca@xxxxxxxxx>
---
arch/arm/boot/dts/Makefile | 1 +
arch/arm/boot/dts/mt6589-fairphone-fp1.dts | 30 ++++++++++++++++++++++
2 files changed, 31 insertions(+)
create mode 100644 arch/arm/boot/dts/mt6589-fairphone-fp1.dts
diff --git a/arch/arm/boot/dts/Makefile b/arch/arm/boot/dts/Makefile
index 7e0934180724..24f402db2613 100644
--- a/arch/arm/boot/dts/Makefile
+++ b/arch/arm/boot/dts/Makefile
@@ -1437,6 +1437,7 @@ dtb-$(CONFIG_ARCH_MEDIATEK) += \
mt2701-evb.dtb \
mt6580-evbp1.dtb \
mt6589-aquaris5.dtb \
+ mt6589-fairphone-fp1.dtb \
mt6592-evb.dtb \
mt7623a-rfb-emmc.dtb \
mt7623a-rfb-nand.dtb \
diff --git a/arch/arm/boot/dts/mt6589-fairphone-fp1.dts
b/arch/arm/boot/dts/mt6589-fairphone-fp1.dts new file mode 100644
index 000000000000..32c14ecf2244
--- /dev/null
+++ b/arch/arm/boot/dts/mt6589-fairphone-fp1.dts
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/*
+ * Copyright (c) 2021, Luca Weiss <luca@xxxxxxxxx>
+ */
+
+/dts-v1/;
+#include "mt6589.dtsi"
+
+/ {
+ model = "Fairphone 1";
+ compatible = "fairphone,fp1", "mediatek,mt6589";
+
+ chosen {
+ stdout-path = &uart3;
+ };
+
+ cpus {
I'd expected "&cpus" why can we overwrite delete the node property like this
here?
Both results in the same, dtc just merges everything together, so as long as
the node name is identical, it works.
Also I cannot use &cpus because cpus in mt6589.dtsi doesn't have a label set.
Then I think we should add a label and use &cpus, as this is the standard way to go.
Regarding SMP:
I have tried setting maxcpus=2 in cmdline and that still makes the kernel
panic. With maxcpus=1 and leaving the deleting out of the dts the kernel is
stable and works properly.
So I think it's better to leave this out of the dts and keep maxcpus=1 in
cmdline (until this gets fixed).
I'd prefer to disable the enable-method in DTS. You can see the four cores up
and running without that, so it seems that is already done in the FW, right?
I've also heard from the person adding enable-method to mt6589.dtsi that it
still works on their board, so something's different, maybe a different SoC
revision, different bootloader behavior or whatever.
Sounds like a different bootloader behaviour.
If that's fine with you, I'll send a v2 with that fixed.
+ /* SMP is not stable on this board, makes the kernel
panic */
+ /delete-property/ enable-method;
+ };
+
+ memory {
Also I was told off-list that this should be called memory@80000000 because of
the reg, will fix in v2.
Correct :)
Thanks,
Matthias
Regards
Luca
+ device_type = "memory";
+ reg = <0x80000000 0x40000000>;
+ };
+};
+
+&uart3 {
+ status = "okay";
+};