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

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Message-ID: <CAOQ1CL7RpygHvzFhPLFsiVB7PFOh2t+_piO5vFJ5V9LCBC_LWg@mail.gmail.com>
Date: Sun, 1 Feb 2026 22:51:02 +0100
From: Liam Mitchell <mitchell.liam@...il.com>
To: Alan Stern <stern@...land.harvard.edu>
Cc: Jiri Kosina <jikos@...nel.org>, Benjamin Tissoires <bentiss@...nel.org>, linux-usb@...r.kernel.org, 
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: usbhid: Intermittent EPROTO errors trigger USB reset and
 interrupt user input

On Sun, 1 Feb 2026 at 21:40, Alan Stern <stern@...land.harvard.edu> 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)
> > - trackpad stops working (see "bcm5974 trackpad broken after USB
> > reset" in linux-input)
> >
> > The keyboard (usbhid) and trackpad (bcm5974) are interfaces of a
> > single full-speed device behind a high-speed hub:
> >
> > /:  Bus 003.Port 001: Dev 001, Class=root_hub, Driver=ehci-pci/2p, 480M
> >     ID 1d6b:0002 Linux Foundation 2.0 root hub
> >     |__ Port 001: Dev 002, If 0, Class=Hub, Driver=hub/8p, 480M
> >         ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
> >         |__ Port 008: Dev 003, If 0, Class=Hub, Driver=hub/2p, 480M
> >             ID 0424:2512 Microchip Technology, Inc. (formerly SMSC) USB 2.0 Hub
> >             |__ Port 002: Dev 005, If 0, Class=Human Interface Device,
> > Driver=usbhid, 12M
> >                 ID 05ac:0259 Apple, Inc. Internal Keyboard/Trackpad
> >             |__ Port 002: Dev 005, If 1, Class=Human Interface Device,
> > Driver=usbhid, 12M
> >                 ID 05ac:0259 Apple, Inc. Internal Keyboard/Trackpad
> >             |__ Port 002: Dev 005, If 2, Class=Human Interface Device,
> > Driver=bcm5974, 12M
> >                 ID 05ac:0259 Apple, Inc. Internal Keyboard/Trackpad
> >
> > Logs preceding one of these events:
> >
> > [19607.563871] bcm5974: bcm5974 3-1.8.2:1.2: trackpad urb status: -71
> > [19611.523681] bcm5974: bcm5974 3-1.8.2:1.2: trackpad urb status: -71
> > [19614.550685] bcm5974: bcm5974 3-1.8.2:1.2: trackpad urb status: -71
> > [19614.563878] usbhid: usbhid 3-1.8.2:1.0: retrying intr urb
> > [19615.050802] bcm5974: bcm5974 3-1.8.2:1.2: trackpad urb status: -71
> > [19615.067673] bcm5974: bcm5974 3-1.8.2:1.2: trackpad urb status: -71
> > [19616.822636] bcm5974: bcm5974 3-1.8.2:1.2: trackpad urb status: -71
> > [19616.835934] usbhid: usbhid 3-1.8.2:1.0: retrying intr urb
> > [19618.126656] bcm5974: bcm5974 3-1.8.2:1.2: trackpad urb status: -71
> > [19618.126711] usbhid: usbhid 3-1.8.2:1.0: resetting device
> > [19618.126728] usbcore: bcm5974 3-1.8.2:1.2: forced unbind
> > [19618.129942] bcm5974: bcm5974 3-1.8.2:1.2: trackpad urb shutting down: -2
> > [19618.155292] usbcore: usb 3-1.8-port2: not reset yet, waiting 10ms
> > [19618.217146] usb 3-1.8.2: reset full-speed USB device number 5 using ehci-pci
> >
> > Both interfaces receive frequent EPROTO errors. I collected statistics
> > on the error interval over a 30 min idle period:
> > Interface, Count, Mean (s), Std Dev (s), Median (s), Min (s), Max (s)
> > Trackpad (bcm5974), 631, 3.21, 4.75, 1.74, 0.01, 35.62
> > Keyboard (usbhid), 71, 26.82, 24.90, 19.34, 0.92, 107.74
>
> There should not be this many EPROTO errors.  The fact that you get them
> indicates some sort of hardware problem.  Have you tried swapping the
> cables, hub, keyboard, and trackpad for different ones to see if that
> makes any difference?

Thanks for the reply,

These are the laptops internal keyboard/trackpad/hub. I would have to
remove the glued-in battery to even unplug the internal cables. If
it's a hardware issue, I'm assuming it was like this out of the
factory.

I haven't had problems with external devices, they go through a
different USB controller.

> > From debugging I understand these to be missed micro-frame (MMF)
> > timing errors in the host controller. They require URB reset but not a
> > reset of the whole device.
> >
> > The bcm5974 driver simply re-submits the interrupt URB. This is the
> > best behavior for these errors on my machine.
> >
> > The more "correct" usbhid driver will delay URB re-submission and even
> > reset the device if a second error is received within a 1.5 second
> > timeout. It's these periods between EPROTO error and re-submission of
> > URB where keyboard events are missed (missed keyup == key stays down
> > and repeats). The default error retry delay of 13ms is relatively
> > small but a full device reset takes about 200ms. With the frequency of
> > errors I'm seeing, every ms counts.
> >
> > Can we improve the usbhid error handling for these cases?
> > 1. Reduce first retry delay from 13ms to 1ms?
> > 2. Reduce the stop retry (reset) timeout from 1.5s to 500ms? 100ms?
> > 3. Require 3 or more errors in the timeout before resetting?
> > 4. Ignore EPROTO errors for known hardware/quirks?
>
> It's possible to do all these things, as far as I know.  However, it
> would be better to eliminate the errors completely.
>
> > Are there ways to differentiate these safe-to-retry MMF/EPROTO errors
> > from others that may really need a full device reset?
>
> Not that I'm aware of, other than just by retrying.
>
> Alan Stern

Liam