Re: [PATCH] platform/chrome: cros_usbpd_notify: Only use parent drvdata when parent is GOOG0004

[wendler . david]

Hi James,

I wanted to report successful testing of this fix on another affected
Chromebook.

Hardware:
- ASUS Chromebook C223NA (BABYMEGA, CORAL)
- Intel Apollo Lake
- Omarchy / Arch Linux, kernel 7.2.5-3-omarchy

Before the fix, disconnecting and reconnecting the USB-C charger could
cause a kernel oops and leave the system unresponsive. On this machine,
GOOG0003:00 has PNP0C09:00 as its parent rather than GOOG0004.

I built and loaded a locally adapted version of cros_usbpd_notify
incorporating the parent-device validation and NULL fallback described
in your patch.

After applying the fix:
- Six consecutive USB-C charger disconnect/reconnect cycles succeeded.
- No kernel oops or system hangs were observed.
- SSH remained responsive throughout testing.
- USB-PD negotiation reached 15V/3A (45W).
- The battery correctly reported Charging after reconnection.

The driver also produced the expected diagnostic message:

  Couldn't get Chrome EC device pointer.

This was a locally adapted implementation rather than a byte-for-byte
build of the submitted patch, but the results support the fix on the
BABYMEGA platform as well.

Thanks for tracking this down!

David