Re: [PATCH] staging: greybus: hid: fix SET_REPORT return value

[Hao-Qun Huang <alvinhuang0603@gmail.com>]

On Jul 9, 2026 at 6:52 PM, Dan Carpenter <error27@gmail.com> wrote:
> These kinds of changes require testing.  How have you tested this
> change?

I compile-tested it (W=1, building gb-hid, greybus and hid together) and
traced the return path by hand.  I don't have Greybus HID hardware and
couldn't find a working emulator (gbsim has been dead since Ara), so I
haven't run it on a live device.

The bug is that gb_hid_set_report() returns -errno on failure and len on
success, and __gb_hid_output_raw_report() computes that into ret (even
adding one back for the report ID byte) and then returns 0, discarding
it.  So a successful hidraw write reports 0 bytes written and a failed
SET_REPORT looks like success.  The GET path next to it already returns
the count, as do usbhid, i2c-hid and uhid, so callers already handle a
positive return and greybus HID was the only one returning 0.

Thanks,
Hao-Qun