Re: [PATCH v3 4/4] arm64: dts: ti: Add support for J784S4 EVM board

From: Andrew Davis
Date: Fri Nov 18 2022 - 13:15:22 EST


On 11/18/22 12:08 PM, Nishanth Menon wrote:
On 11:56-20221118, Andrew Davis wrote:
On 11/18/22 11:47 AM, Nishanth Menon wrote:
On 11:40-20221118, Andrew Davis wrote:
On 11/16/22 7:04 AM, Apurva Nandan wrote:

[...]

+#include <dt-bindings/net/ti-dp83867.h>
+#include <dt-bindings/gpio/gpio.h>
+#include "k3-j784s4.dtsi"
+
+/ {
+ compatible = "ti,j784s4-evm", "ti,j784s4";
+ model = "Texas Instruments J784S4 EVM";
+
+ chosen {
+ stdout-path = "serial2:115200n8";
+ };
+
+ aliases {
+ serial2 = &main_uart8;

This feels hacky. Your chosen node picks serial2 as that is usually
the one that is wired up on K3 boards. But on this board it is main_uart8.
So why not have this be serial10, then choose

stdout-path = "serial10:115200n8";

Also, I've made comments on previous version of this series, it is
nice to include folks who have commented before in the CC for future
versions, that way our filters don't hide these away and we can more
easily check that our comments have been addressed.

Please stick with the standard of serial2 as the linux console standard.
We ended up with that to ease up capabilities of various distros to
uniformly work across SoC and board variants.


The chosen "stdout-path" is for setting the kernel's default output terminal.
Distros and other userspaces need to use their own policy mechanisms for
picking what serial port to run getty on or whatever the issue may be.

Some look at the kernel command line, and our bootloader provides
that too, so still no reason to fake alias names here.


We have had this conversation earlier as well.

https://lore.kernel.org/linux-arm-kernel/CAK8P3a2VSBvOn1o+q1PYZaQ6LS9U4cz+DZGuDbisHkwNs2dAAw@xxxxxxxxxxxxxx/T/#m4ecb0dc6a78c84631f072faa1b0df0df46333d09

This is also the reason why we picked serial2 as linux console as a
standard across the boards based on the ecosystem.


I don't see either of those addressed in that thread, only that
the aliases should go in the .dts files and be trimmed, nothing
stops us from:

chosen {
stdout-path = "serial10:115200n8";
};

aliases {
serial10 = &main_uart8;
};

Andrew