Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Sat, 23 Jan 2021 11:14:18 +0100
From:   Stanislaw Gruszka <stf_xl@wp.pl>
To:     Mathias Nyman <mathias.nyman@linux.intel.com>
Cc:     Greg KH <greg@kroah.com>, linux-usb@vger.kernel.org,
        linux-wireless@vger.kernel.org,
        Mathias Nyman <mathias.nyman@intel.com>,
        Bernhard <bernhard.gebetsberger@gmx.at>
Subject: Re: [PATCH] usb, xhci, rt2800usb: do not perform Soft Retry
Message-ID: <20210123101418.GA16688@wp.pl>
References: <20210122104342.12451-1-stf_xl@wp.pl>
 <YAq9bt6q9dfk4F+F@kroah.com>
 <20210122132650.GA13029@wp.pl>
 <eb37b28d-5046-f0cd-92ee-55af0e350802@linux.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <eb37b28d-5046-f0cd-92ee-55af0e350802@linux.intel.com>
Precedence: bulk

On Fri, Jan 22, 2021 at 05:00:21PM +0200, Mathias Nyman wrote:
> >> Or is this due to the specific host controller device hardware?  Should
> >> this be a xhci quirk for a specific pci device instead?
> 
> Exactly, this should be checked.
> Stanislaw, weren't there a few users already that saw this issue?

There are 30+ users cc-ed in the bugzilla report. However I think some
of them are not affected by issue originally reported by Bernhard.
They just saw "WARN Set TR Deq Ptr cmd failed due to incorrect slot
or ep state" message caused by different problem and added comment
to this particular bug report.

> Do we know what xHCI controllers they were using?

What I can tell issue was reported mostly on ASMedia and AMD
controllers. We can ask for exact vendor and device IDs and
just add xhci->quirks flag.

However I'm not entirely sure that xHCI hardware misbehave
is actual root cause. I think equally probable is that
connected device do not handle soft retry correctly. In that
case disabling Soft Retry per device would be actually
"lightest hammer" since other devices connected to the
xHCI host could benefit from faster recovery.

Is there way to debug/identify which side: host or device
hardware misbehave when Soft Retry is performed ?

Stanislaw