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Message-ID: <063D6719AE5E284EB5DD2968C1650D6D0F6B7707@AcuExch.aculab.com>
Date: Mon, 3 Feb 2014 09:54:09 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'Mark Lord' <mlord@...ox.com>, Ming Lei <ming.lei@...onical.com>
CC: Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
Bjørn Mork <bjorn@...k.no>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
David Miller <davem@...emloft.net>,
"Dan Williams" <dan.j.williams@...el.com>,
"Nyman, Mathias" <mathias.nyman@...el.com>,
Alan Stern <stern@...land.harvard.edu>,
Freddy Xin <freddy@...x.com.tw>
Subject: RE: [PATCH RFC 1/1] usb: Tell xhci when usb data might be misaligned
From: Mark Lord
> On 14-02-01 09:18 AM, Ming Lei wrote:
> >
> > Even real regressions are easily/often introduced, and we are discussing
> > how to fix that. I suggest to unset the flag only for the known buggy
> > controllers.
>
> It is not the controllers that are particularly "buggy" here.
> But rather the drivers and design of parts of the kernel.
I suspect that the documentation is describing the actual implementation
of a specific hardware implementation, not necessarily how the hardware was
intended to behave.
The requirement for two 32bit accesses to a 64bit register is very similar.
This also means that implementations of the hardware that claim conformance
to the 0.96 specification might have similar issues.
Given the small number of xhci controllers and the even smaller number of
VHDL (or similar) sources they will be based on, it really ought to be
possible to tabulate the controller versions and families to get a much
better idea of their behaviour.
I've got two systems with Intel USB3 controllers, linux reports one as
'panther point', the other as '7 Series/C210 Series' (seems to be a Xeon
chipset). I've no idea how the latter relates to the former.
David
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