[Linux-aus] USB-C chargers

[James Henstridge]

On Mon, 28 Nov 2022 at 14:58, Russell Coker via linux-aus
<linux-aus at lists.linux.org.au> wrote:
>
> https://www.austeamhk.com/products/30w-usb-c-power-adapter-charger-for-lenovo-x1-carbon-5th-gen
>
> I have a Thinkpad Carbon X1 Gen5 which shipped with a 65W USB-C PSU and which
> runs well with a 45W USB-C PSU.  The above advert and others like it imply
> that 30W is adequate to power that laptop.
>
> https://www.kogan.com/au/c/black-friday-sale-22-tech/shop/category/phones-accessories-smartphones-accessories-44025/?facet-features-furniture-filterable=GaN+Technology
>
> Kogan offered some deals on GaN chargers, the above is the one that's still on
> sale, they also had a 30W one for $10 which I bought expecting it to work with
> my Thinkpad, but it didn't.
>
> How do I work out why the charger didn't work?  If I buy the 68W version of
> that charger is it likely to work?  Could it be the USB-C - USB-C cables that
> I used (I tested 3 cables of different brands from my collection)?

You can sometimes find some information in /sys/class/typec as described here:

https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-class-typec

However, it really depends on what information the hardware exposes to
the OS. I've got an X1 Gen5, and only a small amount of that info is
exposed (at least on kernel 5.19: there's no ). I think most of the
USB-PD stuff is being handled in the firmware without the OS's
involvement.

The spec sheet for the laptop seems to indicate that it won't fast
charge with the official 45W charger, so I suspect a 30W charger won't
cut it.

https://psref.lenovo.com/syspool/Sys/PDF/ThinkPad/ThinkPad_X1_Carbon_5th_Gen/ThinkPad_X1_Carbon_5th_Gen_Spec.PDF

James.