Date: Fri, 03 Jan 2014 14:12:27 -0500 From: Nathan Whitehorn <nwhitehorn@freebsd.org> To: Markus Pfeiffer <markus.pfeiffer@morphism.de>, Ian Lepore <ian@FreeBSD.org> Cc: freebsd-arm@FreeBSD.org Subject: Re: FreeBSD 10 on Dockstar (Marvell Kirkwood) Message-ID: <52C70B9B.9090205@freebsd.org> In-Reply-To: <20140103175914.GC98342@moore.morphism.de> References: <20131231211054.GA90299@moore.morphism.de> <1388770603.1158.273.camel@revolution.hippie.lan> <20140103175914.GC98342@moore.morphism.de>
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On 01/03/14 12:59, Markus Pfeiffer wrote: > Hi Ian, > > On Fri, Jan 03, 2014 at 10:36:43AM -0700, Ian Lepore wrote: >> On Tue, 2013-12-31 at 21:10 +0000, Markus Pfeiffer wrote: >>> Hi all, >>> >>> I managed "fixing" it by editing the dockstar.dts file and putting for ranges: >>> >>> ranges = <0x0 0x2f 0xf9300000 0x00100000> >>> >>> Now I just have to figure out why this "fixes" it, and what damage that patch >>> does. >>> I also have some pathces for the LED on the dockstar which will tip up in my >>> github soon. >>> >>> Cheers, >>> markus >> After looking at the marvell code and docs, and some info I found about >> the dockstar at OpenWRT.org, I think the attached patch is the right fix >> for a dockstar (it maps the nand flash, and removes mappings for NOR >> flash and an LED; the dockstar doesn't seem to have NOR flash, and the >> LED thing seems to be out of place). >> > Can I find information anywhere as to what this ranges command actually means? > I was assuming it has something to do with memory mappings, but I didn't find > any info as to what in particular the 0x2f _means_. > > The ranges field, as per IEEE 1275 (page 175), provides a mapping from addresses in a child address space to the parent. It is a set of tuples of (child base address, parent base address, size), with the field widths being (#address-cells on this node [2], #address-cells of parent bus [1], #size-cells on this node [1]). This mapping table is used for resource allocation of children, to map bus-local requests for addresses to addresses on the parent bus (in this case, physical memory addresses). In this case, the following: ranges = <0x0 0x2f 0xf9300000 0x00100000> means that addresses 0x2f-0x0010002f in "localbus" should map linearly to physical addresses 0xf9300000-0xf9310000. This is used for drivers on the attached sub-bus so that their resources (in the "reg" properties, or in "ranges" if there are further sub-buses) can be specified in bus-local address units. The kernel code probably misinterprets it badly if changing this affects anything, which in turn implies that our kernel code is horribly bug-riddled. Note also that this replacement is not equivalent to the old mappings, since it shifts all the mappings downward by 0x20 bytes. -Nathan
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