Re: [PATCH v2] of: property: fw_devlink: Add support for "phy-handle" property

[Saravana Kannan]

On Tue, Aug 24, 2021 at 12:03 AM Marek Szyprowski
<m.szyprowski@xxxxxxxxxxx> wrote:
>
> Hi,
>
> On 23.08.2021 20:22, Saravana Kannan wrote:
> > On Mon, Aug 23, 2021 at 5:08 AM Marek Szyprowski
> > <m.szyprowski@xxxxxxxxxxx> wrote:
> >> On 18.08.2021 04:17, Saravana Kannan wrote:
> >>> Allows tracking dependencies between Ethernet PHYs and their consumers.
> >>>
> >>> Cc: Andrew Lunn <andrew@xxxxxxx>
> >>> Cc: netdev@xxxxxxxxxxxxxxx
> >>> Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx>
> >> This patch landed recently in linux-next as commit cf4b94c8530d ("of:
> >> property: fw_devlink: Add support for "phy-handle" property"). It breaks
> >> ethernet operation on my Amlogic-based ARM64 boards: Odroid C4
> >> (arm64/boot/dts/amlogic/meson-sm1-odroid-c4.dts) and N2
> >> (meson-g12b-odroid-n2.dts) as well as Khadas VIM3/VIM3l
> >> (meson-g12b-a311d-khadas-vim3.dts and meson-sm1-khadas-vim3l.dts).
> >>
> >> In case of OdroidC4 I see the following entries in the
> >> /sys/kernel/debug/devices_deferred:
> >>
> >> ff64c000.mdio-multiplexer
> >> ff3f0000.ethernet
> >>
> >> Let me know if there is anything I can check to help debugging this issue.
> > I'm fairly certain you are hitting this issue because the PHY device
> > doesn't have a compatible property. And so the device link dependency
> > is propagated up to the mdio bus. But busses as suppliers aren't good
> > because busses never "probe".
> >
> > PHY seems to be one of those cases where it's okay to have the
> > compatible property but also okay to not have it. You can confirm my
> > theory by checking for the list of suppliers under
> > ff64c000.mdio-multiplexer. You'd see mdio@0 (ext_mdio) and if you look
> > at the "status" file under the folder it should be "dormant". If you
> > add a compatible property that fits the formats a PHY node can have,
> > that should also fix your issue (not the solution though).
>
> Where should I look for the mentioned device links 'status' file?
>
> # find /sys -name ff64c000.mdio-multiplexer
> /sys/devices/platform/soc/ff600000.bus/ff64c000.mdio-multiplexer
> /sys/bus/platform/devices/ff64c000.mdio-multiplexer
>
> # ls -l /sys/devices/platform/soc/ff600000.bus/ff64c000.mdio-multiplexer
> total 0

This is the folder I wanted you to check.

> lrwxrwxrwx 1 root root    0 Jan  1 00:04
> consumer:platform:ff3f0000.ethernet ->
> ../../../../virtual/devlink/platform:ff64c000.mdio-multiplexer--platform:ff3f0000.ethernet

But I should have asked to look for the consumer list and not the
supplier list. In any case, we can see that the ethernet is marked as
the consumer of the mdio-multiplexer instead of the PHY device. So my
hunch seems to be right.

> -rw-r--r-- 1 root root 4096 Jan  1 00:04 driver_override
> -r--r--r-- 1 root root 4096 Jan  1 00:04 modalias
> lrwxrwxrwx 1 root root    0 Jan  1 00:04 of_node ->
> ../../../../../firmware/devicetree/base/soc/bus@ff600000/mdio-multiplexer@4c000
> drwxr-xr-x 2 root root    0 Jan  1 00:02 power
> lrwxrwxrwx 1 root root    0 Jan  1 00:04 subsystem ->
> ../../../../../bus/platform
> lrwxrwxrwx 1 root root    0 Jan  1 00:04
> supplier:platform:ff63c000.system-controller:clock-controller ->
> ../../../../virtual/devlink/platform:ff63c000.system-controller:clock-controller--platform:ff64c000.mdio-multiplexer
> -rw-r--r-- 1 root root 4096 Jan  1 00:04 uevent
> -r--r--r-- 1 root root 4096 Jan  1 00:04 waiting_for_supplier
>
> # cat
> /sys/devices/platform/soc/ff600000.bus/ff64c000.mdio-multiplexer/waiting_for_supplier
> 0
>
> I'm also not sure what compatible string should I add there.

It should have been added to external_phy: ethernet-phy@0. But don't
worry about it (because you need to use a specific format for the
compatible string).

-Saravana

>
> > I'll send out a fix this week (once you confirm my analysis). Thanks
> > for reporting it.
>
> Best regards
>
> --
> Marek Szyprowski, PhD
> Samsung R&D Institute Poland
>