Re: [PATCH rtw-next v2 1/1] wifi: rtw89: usb: Support switching to USB 3 mode

[Devin Wittmayer <lucid_duck@justthetip.ca>]

On Mon, 2026-05-11 at 19:26 +0200, Johannes Berg wrote:
> > +static bool rtw89_switch_usb_mode = true;
> > +module_param_named(switch_usb_mode, rtw89_switch_usb_mode, bool, 0644);
> > +MODULE_PARM_DESC(switch_usb_mode,
> > +         "Set to N to disable switching to USB 3 mode to avoid potential interference in the 2.4 GHz band (default: Y)");
>
> We shouldn't really add new module parameters.

This module parameter follows the pattern Bitterblue established for
rtw88: same user-facing name (switch_usb_mode), same description, same
default. Commit 315c23a64e99 "wifi: rtw88: usb: Support USB 3 with
RTL8822CU/RTL8822BU" (2024-07-10) added it to rtw88/usb.c and it
remains in-tree.

Three v3 paths I see:

1. Drop the param. Users hitting USB3 2.4 GHz harmonic interference
   would need to use a USB 2 port instead.
2. Move the escape hatch behind a sysfs or nl80211 control. New UABI
   surface; open to design suggestions on that.
3. Keep it for rtw89/rtw88 symmetry on the same USB3 / 2.4 GHz
   harmonic interference issue.

Any of the three works on my side. If the rtw88 param is grandfathered
and we should not add new module parameters even in this case, I will
respin without it in v3.

Devin