linux-kernel - Re: [PATCH] usb: xhci: make XHCI_STOP_EP_CMD

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Date:   Tue, 08 Mar 2022 17:17:23 +0100
From:   Martin Kepplinger <martin.kepplinger@...i.sm>
To:     Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Greg KH <gregkh@...uxfoundation.org>
Cc:     mathias.nyman@...el.com, kernel@...i.sm, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: xhci: make XHCI_STOP_EP_CMD_TIMEOUT a module
 parameter

Am Montag, dem 07.03.2022 um 10:49 +0200 schrieb Mathias Nyman:
> On 4.3.2022 16.17, Greg KH wrote:
> > On Fri, Mar 04, 2022 at 12:30:57PM +0100, Martin Kepplinger wrote:
> > > On the Librem 5 imx8mq system we've seen the stop endpoint
> > > command
> > > time out regularly which results in the hub dying.
> > > 
> > > While on the one hand we see "Port resume timed out, port 1-1:
> > > 0xfe3"
> > > before this and on the other hand driver-comments suggest that
> > > the driver
> > > might be able to recover instead of dying here, Sarah seemed to
> > > have a
> > > workaround for this particulator problem in mind already:
> > > 
> > > Make it a module parameter. So while it might not be the root
> > > cause for
> > > the problem, do this to give users a workaround.
> > 
> > This is not the 1990's, sorry, please do not add new module
> > parameters.
> > They modify code, when you want to modify an individual device.
> > 
> 
> Agree, I think we really need to find the rootcause here.
> 
> There's a known problem with this stop endpoint timeout timer.
> 
> For all other commands we start the timer when the controller starts
> processing the
> command, but the stop endpoint timer is started immediately when
> command is queued.
> So it might timeout if some other commend before it failed.
> 
> I have a patchseries for this. It's still work in progress but should
> be testable.
> Pushed to a branch named stop_endpoint_fixes
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git
> stop_endpoint_fixes
> https://git.kernel.org/pub/scm/linux/kernel/git/mnyman/xhci.git/log/?h=stop_endpoint_fixes
> 
> Can you try it out and see if it helps?
> 

thanks a lot Mathias, I'm running these now. The timeout has not been
easy to reproduce (or I'm just lazy) but in a few days I should be able
to tell whether that helps.

So this thread has been about

[14145.960512] xhci-hcd xhci-hcd.4.auto: Port resume timed out, port 1-
1: 0xfe3
[14156.308511] xhci-hcd xhci-hcd.4.auto: xHCI host not responding to
stop endpoint command.

that I previously tried to work around by increasing
XHCI_MAX_REXIT_TIMEOUT_MS and XHCI_STOP_EP_CMD_TIMEOUT.


These patches can't help with the following, right?
readl_poll_timeout_atomic() with a fixed timeout is called in this
case:

xhci-hcd xhci-hcd.4.auto: Abort failed to stop command ring: -110

I see that too from time to time. It results in the HC dying as well.

thanks,
                              martin