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Subject: Re: [PATCH] usb, xhci, rt2800usb: do not perform Soft Retry
To:     Mathias Nyman <mathias.nyman@linux.intel.com>,
        Greg KH <greg@kroah.com>, stf_xl@wp.pl
Cc:     linux-usb@vger.kernel.org, linux-wireless@vger.kernel.org,
        Mathias Nyman <mathias.nyman@intel.com>,
        Bernhard <bernhard.gebetsberger@gmx.at>
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 <4690235c-9676-7985-12a1-b8bcfd195a43@linux.intel.com>
From:   Andreas Hartmann <andihartmann@01019freenet.de>
Message-ID: <43ebb270-2069-4672-f277-1222979305a8@01019freenet.de>
Date:   Fri, 22 Jan 2021 18:16:21 +0100
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Precedence: bulk

On 22.01.21 at 16:22 Mathias Nyman wrote:
> On 22.1.2021 15.17, Andreas Hartmann wrote:
>> But anyway, there is from my point of view a basic problem with xhci_hcd,
>> which just seems not to be completely backward compatible to existing USB 2
>> drivers (see https://marc.info/?l=linux-usb&m=161130327411612&w=2) if the
>> device is plugged to an USB 3.x interface.
> 
> This looks like a different issue, lets keep it in its own thread.
> 
> The xHCI usb host controller handles both USB 2 and USB 3 speeds.
> If the USB port is connected to a xHC controller then the xhci driver will
> be used. If the port is connected to a EHCI then the ehci driever is used.
> EHCI does not support USB3 speeds.
> 
> It's very possible that something that worked behind a EHCI host has issues
> when connected to a xHCI host.

I would be very glad to get this sorted out. At the moment I absolutely
don't know where exactly to try to prevent to trigger the "xhci_hcd
0000:05:00.3: WARN Wrong bounce buffer write length: 0 != 512"
situation. Is it on the level where the bulk packages are created or
even before?


Thanks
Andreas