[PATCH v2] ARM: dts: aspeed: zaius add reg field to pca9541a i2c mux

[Joel Stanley]

Hey Emily,

Welcome to OpenBMC! I maintain the kernel tree for the project.

When you're sending patches for our fork of Linux I encourage
developers to put the project and branch they're targeting in the
patch prefix. This helps me out as we use the list for a few things
other than Linux:

https://github.com/openbmc/linux/wiki/TipsAndTricks#sending-patches

git format-patch --subject-prefix="PATCH linux dev-4.7"

On Thu, Mar 2, 2017 at 9:13 AM, Emily Shaffer <emilyshaffer at google.com> wrote:
> I2C mux pca9541a at 70 for Zaius was incorrectly configured, preventing
> hotswap at 10 LM5066I hotswap controller from being configured at startup.
> Adding the missing field results in the hotswap controller being present
> immediately at boot.

I wasn't sure why this would fix things. I had a chat with Xo and he explained:

09:28 <@shenki> GHF[m]: but i wasn't sure why adding the reg property
changed things?
09:28 <@shenki> GHF[m]: was it not binding without the reg?
09:28 <@shenki> there's no device tree bindings that match what zaius
is doing, so it's hard to check
10:44 < GHF[m]> shenki: correct, no i2c slave device for the hotswap
controller was instantiated and the lm5066 driver did not bind
10:45 < GHF[m]> shenki: actually Emily noted that it did bind if the
device name were changed to "lm5066" suggesting that the of_*
compatible property match wasn't working
10:46 < GHF[m]> shenki: no idea why the reg property one level up
affects that ¯_(ツ)_/¯
10:47 <@shenki> GHF[m]: okay. i will merge it for now

I've applied your patch to dev-4.7 with Xo's review.

Cheers,

Joel

> Signed-off-by: Emily Shaffer <emilyshaffer at google.com>
> ---
>  arch/arm/boot/dts/aspeed-bmc-opp-zaius.dts | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm/boot/dts/aspeed-bmc-opp-zaius.dts b/arch/arm/boot/dts/aspeed-bmc-opp-zaius.dts
> index 548ef1e939fe..7015863751e0 100644
> --- a/arch/arm/boot/dts/aspeed-bmc-opp-zaius.dts
> +++ b/arch/arm/boot/dts/aspeed-bmc-opp-zaius.dts
> @@ -258,6 +258,7 @@
>                 i2c-arb {
>                         #address-cells = <1>;
>                         #size-cells = <0>;
> +                       reg = <0x0>;
>
>                         hotswap at 10 {
>                                 compatible = "ti,lm5066";
> --
> 2.12.0.rc1.440.g5b76565f74-goog
>