From: Peter Stuge <peter@stuge.se>
To: David Laight <David.Laight@ACULAB.COM>
Cc: 'Sarah Sharp' <sarah.a.sharp@linux.intel.com>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
David Miller <davem@davemloft.net>,
Dan Williams <dan.j.williams@intel.com>,
"Nyman, Mathias" <mathias.nyman@intel.com>,
Mark Lord <mlord@pobox.com>,
Alan Stern <stern@rowland.harvard.edu>,
Freddy Xin <freddy@asix.com.tw>
Subject: Re: [PATCH RFC 1/1] usb: Tell xhci when usb data might be misaligned
Date: Fri, 31 Jan 2014 14:21:46 +0100 [thread overview]
Message-ID: <20140131132146.2833.qmail@stuge.se> (raw)
In-Reply-To: <063D6719AE5E284EB5DD2968C1650D6D0F6B5B78@AcuExch.aculab.com>
David Laight wrote:
> > We shouldn't need to make userspace start to worry about alignment at
> > all. libusb worked in the past, before the link TRB fix went in. We
> > *cannot* break userspace USB drivers. The breakage needs to be fixed in
> > the USB core or the xHCI driver.
>
> Userspace doesn't care since everything gets copied into aligned
> kernel fragments - otherwise the other usb controllers wouldn't work.
OK, but not so great if someone wants to squeeze the most performance
possible out of USB also from userspace.
I'm going off on a tangent now but would it make sense to allow
userspace to do alignment if it wants to, and have a way to tell
the kernel when urb buffers are pre-aligned?
//Peter
next prev parent reply other threads:[~2014-01-31 13:21 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-30 21:18 [PATCH RFC 1/1] usb: Tell xhci when usb data might be misaligned Sarah Sharp
2014-01-30 21:39 ` Mark Lord
2014-01-30 21:42 ` Mark Lord
2014-01-30 21:43 ` Alan Stern
2014-01-30 21:48 ` Mark Lord
2014-01-30 21:55 ` Sarah Sharp
2014-01-30 22:05 ` Bjørn Mork
2014-01-30 22:07 ` Alan Stern
2014-01-30 21:50 ` Bjørn Mork
2014-01-30 22:15 ` Sarah Sharp
2014-01-31 0:17 ` Ming Lei
2014-01-31 19:00 ` Sarah Sharp
2014-02-01 7:54 ` Ming Lei
2014-02-01 13:30 ` Mark Lord
2014-02-01 14:18 ` Ming Lei
2014-02-01 20:05 ` Mark Lord
[not found] ` <52ED5381.2010106-e+AXbWqSrlAAvxtiuMwx3w@public.gmane.org>
2014-02-03 9:54 ` David Laight
2014-02-03 17:56 ` Sarah Sharp
2014-02-03 17:55 ` Sarah Sharp
2014-01-31 15:22 ` David Laight
2014-01-31 10:14 ` David Laight
2014-01-31 13:21 ` Peter Stuge [this message]
2014-01-31 13:52 ` David Laight
-- strict thread matches above, loose matches on Subject: below --
2014-01-30 16:00 David Laight
[not found] ` <063D6719AE5E284EB5DD2968C1650D6D0F6B5486-VkEWCZq2GCInGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
2014-01-30 16:17 ` Peter Stuge
[not found] ` <20140130161721.25560.qmail-Y+HMSxxDrH8@public.gmane.org>
2014-01-30 16:30 ` David Laight
[not found] ` <063D6719AE5E284EB5DD2968C1650D6D0F6B553D-VkEWCZq2GCInGFn1LkZF6NBPR1lH4CV8@public.gmane.org>
2014-01-30 16:35 ` Peter Stuge
2014-01-31 9:30 ` David Laight
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