Re: usbhid: Intermittent EPROTO errors trigger USB reset and interrupt user input

[Alan Stern]

On Mon, Feb 02, 2026 at 04:48:49PM +0100, Oliver Neukum wrote:
> 
> 
> On 01.02.26 21:40, Alan Stern wrote:
> > On Sun, Feb 01, 2026 at 06:57:06PM +0100, Liam Mitchell wrote:
> > > Hi,
> > > 
> > > I'm trying to understand and fix intermittent keyboard/trackpad issues
> > > on my 2013 MacBook Pro running Linux v6.18.4:
> > > - missed/repeated/sticky keys while typing (this thread)
> 
> Alan,
> 
> this raises a question. What happens to KEY_UP events generated in
> between the last EPROTO and the reset? It seems to me like we need
> to assume that a reset implies that all keys have been released.

That question is specialized to keyboards.  You could ask a similar 
question about mouse buttons, or other input (or output!) devices.

But it's a good point.  There should be some sort of callback to inform 
HID drivers that their device has been reset, so they could reset 
whatever internal state they are maintaining.

This sounds like something going way beyond usbhid, though.  And it 
probably would not crop up very often, so it wouldn't get much testing.  
Liam's computer seems to be pretty unusual.

Alan Stern