Date: Tue, 07 Jan 2014 23:19:38 -0500 From: Nathan Whitehorn <nwhitehorn@freebsd.org> To: Ian Lepore <ian@FreeBSD.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r260440 - head/sys/arm/conf Message-ID: <52CCD1DA.7010008@freebsd.org> In-Reply-To: <201401080340.s083eIDG054652@svn.freebsd.org> References: <201401080340.s083eIDG054652@svn.freebsd.org>
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On 01/07/14 22:40, Ian Lepore wrote: > Author: ian > Date: Wed Jan 8 03:40:18 2014 > New Revision: 260440 > URL: http://svnweb.freebsd.org/changeset/base/260440 > > Log: > Add option USB_HOST_ALIGN to configs that contain 'device usb'. Setting > this to the cache line size is required to avoid data corruption on armv4 > and armv5, and improves performance on armv6, in both cases by avoiding > partial cacheline flushes for USB IO. > > All these configs already exist in 10-stable. A few that don't (and > thus can't be MFC'd yet) will be committed separately. > There has to be -- and I do not mean this as a criticism of your patch -- a better solution to this problem than USB_HOST_ALIGN. Isn't busdma supposed to handle this kind of thing? Why is USB different? -Nathan
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