From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [203.10.76.45]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mx.ozlabs.org", Issuer "CA Cert Signing Authority" (verified OK)) by bilbo.ozlabs.org (Postfix) with ESMTPS id DE51BB707B for ; Fri, 10 Jul 2009 05:35:23 +1000 (EST) Received: from ovro.ovro.caltech.edu (ovro.ovro.caltech.edu [192.100.16.2]) by ozlabs.org (Postfix) with ESMTP id 3743FDDDE7 for ; Fri, 10 Jul 2009 05:35:22 +1000 (EST) Date: Thu, 9 Jul 2009 12:35:19 -0700 From: "Ira W. Snyder" To: Kumar Gala Subject: Re: [PATCH] edac: mpc85xx: add support for mpc83xx memory controller Message-ID: <20090709193519.GE29383@ovro.caltech.edu> References: <20090708161954.GC14979@ovro.caltech.edu> <3887C2A7-3566-43A9-A863-4670B039E5DA@kernel.crashing.org> <20090708193355.GE2827@ovro.caltech.edu> <6CF38C94-45EB-4FD7-B8E0-B9899F4EEF90@kernel.crashing.org> <20090709165844.GB29383@ovro.caltech.edu> <20090709181705.GD29383@ovro.caltech.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Cc: linuxppc-dev@ozlabs.org, bluesmoke-devel@lists.sourceforge.net, Dave Jiang List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, Jul 09, 2009 at 01:25:43PM -0500, Kumar Gala wrote: > > On Jul 9, 2009, at 1:17 PM, Ira W. Snyder wrote: > >> On Thu, Jul 09, 2009 at 12:58:53PM -0500, Kumar Gala wrote: >>>> Hello Kumar, >>>> >>>> I must not understand something going on here. Your proposed code >>>> doesn't work at all on my board. The >>>> /sys/devices/system/edac/mc/mc0/size_mb doesn't come out correctly. >>> >>> What does it come out as? How much memory do you have in the system? >>> >> >> The size_mb shows as 0 with your code. See the explanation below. With >> my code it shows as 256MB, as expected. >> >> I have 256MB memory in the system. >> >>>> The attached patch DOES work on my board, but I'm confident that it >>>> does >>>> NOT work on a system with PAGE_SIZE != 4096. Any idea what I did >>>> wrong? >>>> >>>> If I'm reading things correctly: >>>> csrow->first_page full address of the first page (NOT pfn) >>>> csrow->last_page full address of the last page (NOT pfn) >>>> csrow->nr_pages number of pages >>>> >>>> The EDAC subsystem does csrow->nr_pages * PAGE_SIZE to get the >>>> size_mb >>>> sysfs value. >>>> >>>> If csrow->first_page and csrow->last_page ARE supposed to be the >>>> pfn, >>>> then I think the original code got it wrong, and the calculation for >>>> csrow->nr_pages needs to be changed. >>>> >>>> Thanks, >>>> Ira >>> >>> [snip] >>> >>>> /************************ MC SYSFS parts >>>> ***********************************/ >>>> >>>> @@ -790,18 +792,19 @@ static void __devinit >>>> mpc85xx_init_csrows(struct >>>> mem_ctl_info *mci) >>>> csrow = &mci->csrows[index]; >>>> cs_bnds = in_be32(pdata->mc_vbase + MPC85XX_MC_CS_BNDS_0 + >>>> (index * MPC85XX_MC_CS_BNDS_OFS)); >>>> - start = (cs_bnds & 0xfff0000) << 4; >>>> - end = ((cs_bnds & 0xfff) << 20); >>>> - if (start) >>>> - start |= 0xfffff; >>>> - if (end) >>>> - end |= 0xfffff; >>> >>> can you printk what cs_bnds values are in your setup. >>> >> >> I am only using a single chip select. CS0_BNDS (register 0xe0002000) >> is >> 0x0000000F. >> >>>> + >>>> + start = (cs_bnds & 0xffff0000) >> 16; >>>> + end = (cs_bnds & 0x0000ffff); >>>> >> >> This is the same in both our versions. >> >> start == 0x0 >> end == 0xF >> >>>> if (start == end) >>>> continue; /* not populated */ >>>> >>>> - csrow->first_page = start >> PAGE_SHIFT; >>>> - csrow->last_page = end >> PAGE_SHIFT; >>>> + start <<= PAGE_SHIFT; >>>> + end <<= PAGE_SHIFT; >>>> + end |= (1 << PAGE_SHIFT) - 1; >>>> + >> >> MY VERSION >> >> start == 0x0 >> end == 0xffff >> >> first_page == 0x0 >> last_page == 0xffff >> >> YOUR VERSION (<<= (20 - PAGE_SHIFT), etc.) > > My math was wrong it should be ( <<= (24 - PAGE_SHIFT) ) > > With that I think things work out. > Yep, that works out great. This solution is much better than my original code. The 83xx doesn't need to be special-cased anymore. I checked the math for a 85xx with 64GB of memory. Assuming it uses 64K pages (PAGE_SHIFT == 16), then everything works out. I'll submit a new patch now. Thanks for the help, Ira