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From: Robert Munteanu <>
To: Greg Kroah-Hartman <>
Cc: Mathias Nyman <>,,,,
Subject: Re: Regression: plugging in USB scanner breaks all USB functionality
Date: Fri, 03 Dec 2021 16:33:23 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Thu, 2021-12-02 at 16:17 +0100, Greg Kroah-Hartman wrote:
> On Thu, Dec 02, 2021 at 03:55:44PM +0100, Robert Munteanu wrote:
> > Hi,
> > 
> > After updating from kernel 5.14.11 to 5.14.14 I am seeing the
> > following
> > problem:
> Can you run 'git bisect' between those kernel versions to get the
> offending commit located?  It shouldn't take that long as there's not a
> lot of changes there.

A full bisect run, as suspected in other messages, results in

e54abefe703ab7c4e5983e889babd1447738ca42 is the first bad commit
commit e54abefe703ab7c4e5983e889babd1447738ca42
Author: Pavankumar Kondeti <>
Date:   Fri Oct 8 12:25:46 2021 +0300

    xhci: Fix command ring pointer corruption while aborting a command
    commit ff0e50d3564f33b7f4b35cadeabd951d66cfc570 upstream.
    The command ring pointer is located at [6:63] bits of the command
    ring control register (CRCR). All the control bits like command
    abort are located at [0:3] bits. While aborting a command, we read
    CRCR and set the abort bit and write to the CRCR. The read will
    give command ring pointer as all zeros. So we essentially write
    the control bits. Since we split the 64 bit write into two 32 bit
    there is a possibility of xHC command ring stopped before the upper
    dword (all zeros) is written. If that happens, xHC updates the
    dword of its internal command ring pointer with all zeros. Next
    when the command ring is restarted, we see xHC memory access
    Fix this issue by only writing to the lower dword of CRCR where all
    control bits are located.
    Signed-off-by: Pavankumar Kondeti <>
    Signed-off-by: Mathias Nyman <>
    Signed-off-by: Greg Kroah-Hartman <>

 drivers/usb/host/xhci-ring.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

I will try the patch linked by Matias as soon as the openSUSE kernel
build is complete.


  reply	other threads:[~2021-12-03 15:33 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-02 14:55 Robert Munteanu
2021-12-02 15:13 ` Thorsten Leemhuis
2021-12-03 17:24   ` Regression: plugging in USB scanner breaks all USB functionality #forregzbot Thorsten Leemhuis
2021-12-04 10:03     ` Greg KH
2021-12-04 10:26       ` Regression: plugging in USB scanner breaks all USB functionality Thorsten Leemhuis
2021-12-04 10:44         ` Greg KH
2021-12-04 11:06           ` Thorsten Leemhuis
2021-12-02 15:17 ` Greg Kroah-Hartman
2021-12-03 15:33   ` Robert Munteanu [this message]
2021-12-03 10:57 ` Mathias Nyman
2021-12-03 11:36   ` Takashi Iwai
2021-12-03 16:22     ` Robert Munteanu

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