Le 22/08/2024 à 03:11, Stuart a écrit :

quoted

If I recollect correctly, there may be an alignment issue and just using
the stack is not enough to guaranty what is needed.

I can't find any reference to issues with it, I'm not sure what I saw before.
Also, it seems like the hid-asus driver is using it:
https://elixir.bootlin.com/linux/v6.11-rc4/source/drivers/hid/hid-asus.c#L391

Stuart

It's not.

asus_kbd_set_report() is called, and there, the array is explicitly 
kmemdup()'ed to a variable called dmabuf before calling 
hid_hw_raw_request().



I've not found an explicit documentation, but here are a few results 
from Google related to HID and DMA related issues:


[1]: 
https://linux.kernel.narkive.com/2bRjLz9p/patch-hid-lenovo-don-t-use-stack-variables-for-dma-buffers

[2]: https://bugzilla.kernel.org/show_bug.cgi?id=87991

[3]: 
https://git.kontron-electronics.de/estoll/linux-stm-lvds/-/commit/3d1355b3cfad53feba76a73b052c757a7de7f4de

CJ