Kevin Hilman [off-list ref] writes:

Saravana Kannan [off-list ref] writes:

quoted

On Mon, Jan 31, 2022 at 7:18 PM Kevin Hilman [off-list ref] wrote:

quoted

Hi Saravana,

Saravana Kannan [off-list ref] writes:

quoted

fw_devlink could end up creating device links for bus only devices.
However, bus only devices don't get probed and can block probe() or
sync_state() [1] call backs of other devices. To avoid this, probe these
devices using the simple-pm-bus driver.

However, there are instances of devices that are not simple buses (they get
probed by their specific drivers) that also list the "simple-bus" (or other
bus only compatible strings) in their compatible property to automatically
populate their child devices. We still want these devices to get probed by
their specific drivers. So, we make sure this driver only probes devices
that are only buses.

[1] - https://lore.kernel.org/lkml/CAPDyKFo9Bxremkb1dDrr4OcXSpE0keVze94Cm=zrkOVxHHxBmQ@mail.gmail.com/ (local)
Fixes: c442a0d18744 ("driver core: Set fw_devlink to "permissive" behavior by default")
Signed-off-by: Saravana Kannan <redacted>
Tested-by: Saravana Kannan <redacted>
Tested-by: Ulf Hansson <redacted>

This patch landed in stable/linux-5.10.y as commit d5f13bbb5104 and it
broke suspend/resume on at least one TI AM335x board I'm testing on:
upstream dts: arch/arm/boot/dts/am335x-icev2.dts, upstream defconfig:
arch/arm/configs/omap2plus_defconfig.

Bisecting between vanilla v5.10 (good) and stable/linux-5.10.y (bad)
pointed me to this patch, and I confirmed that reverting just this patch
on top of stable/linux-5.10.y makes it work again.

Also interesting, this same platform works fine on vanilla v5.15, which
also includes this patch.  That suggests that either 1) this patch
should not have been backported to v5.10 stable or 2) there are some
other dependencies that are missing in v5.10.

Since vanilla v5.10 works fine, I'm leaning towards (1), but if you have
any ideas for deps that need backporting, I'm happy to try.

Oh wow! I didn't realize I made so many changes AFTER 5.10! Unless I'm
doing something wrong with my git commands.
$ git log v5.10..v5.15 --oneline -- drivers/of/property.c
$ git log v5.10..v5.15 --oneline --author=saravanak -- drivers/base/

If you don't think I got my git command completely wrong, yeah, way
too many patches are missing on 5.10. I'd go with the option of
dropping this patch on 5.10.

I agree.  Could you submit a revert for v5.10 stable?  As the patch
author, it's probably better if it comes from you.

Nevermind, I'm impatient and submitted a revert to stable[1] :)

Kevin

[1] https://lore.kernel.org/stable/20220202195705.3598798-1-khilman@baylibre.com/ (local)

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