From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f46.google.com ([209.85.220.46]:36132 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933181AbbHKCul (ORCPT ); Mon, 10 Aug 2015 22:50:41 -0400 Received: by pacrr5 with SMTP id rr5so116659516pac.3 for ; Mon, 10 Aug 2015 19:50:40 -0700 (PDT) Subject: Re: [PATCH v6 18/42] powerpc/powernv: Allocate PE# in deasending order To: Gavin Shan References: <1438834307-26960-1-git-send-email-gwshan@linux.vnet.ibm.com> <1438834307-26960-19-git-send-email-gwshan@linux.vnet.ibm.com> <55C8B786.1050702@ozlabs.ru> <20150811004339.GC18981@gwshan> Cc: linuxppc-dev@lists.ozlabs.org, linux-pci@vger.kernel.org, devicetree@vger.kernel.org, benh@kernel.crashing.org, mpe@ellerman.id.au, bhelgaas@google.com, grant.likely@linaro.org, robherring2@gmail.com, panto@antoniou-consulting.com From: Alexey Kardashevskiy Message-ID: <55C962F9.2080105@ozlabs.ru> Date: Tue, 11 Aug 2015 12:50:33 +1000 MIME-Version: 1.0 In-Reply-To: <20150811004339.GC18981@gwshan> Content-Type: text/plain; charset=koi8-r; format=flowed Sender: linux-pci-owner@vger.kernel.org List-ID: On 08/11/2015 10:43 AM, Gavin Shan wrote: > On Tue, Aug 11, 2015 at 12:39:02AM +1000, Alexey Kardashevskiy wrote: >> On 08/06/2015 02:11 PM, Gavin Shan wrote: >>> The available PE#, represented by a bitmap in the PHB, is allocated >>> in ascending order. >> >> Available PE# is available exactly because it is not allocated ;) >> > > Yeah, will correct it. > >>> It conflicts with the fact that M64 segments are >>> assigned in same order. In order to avoid the conflict, the patch >>> allocates PE# in descending order. >> >> What kind of conflict? >> > > On PHB3, the M64 segment is assigned to one PE whose PE number is > determined. M64 segment are allocated in ascending order. It's why > I would like to allocate PE# in deascending order. From previous lessons, I thought M64 segment number is PE# number as well :-/ Seems this is not the case, so what does store this seg#<->PE# mapping in PHB? > >>> >>> Signed-off-by: Gavin Shan >>> --- >>> arch/powerpc/platforms/powernv/pci-ioda.c | 11 ++++++++--- >>> 1 file changed, 8 insertions(+), 3 deletions(-) >>> >>> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c >>> index 56b058c..1c950e8 100644 >>> --- a/arch/powerpc/platforms/powernv/pci-ioda.c >>> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c >>> @@ -161,13 +161,18 @@ static struct pnv_ioda_pe *pnv_ioda_reserve_pe(struct pnv_phb *phb, int pe_no) >>> static struct pnv_ioda_pe *pnv_ioda_alloc_pe(struct pnv_phb *phb) >>> { >>> unsigned long pe; >>> + unsigned long limit = phb->ioda.total_pe_num - 1; >>> >>> do { >>> pe = find_next_zero_bit(phb->ioda.pe_alloc, >>> - phb->ioda.total_pe_num, 0); >>> - if (pe >= phb->ioda.total_pe_num) >>> + phb->ioda.total_pe_num, limit); >>> + if (pe < phb->ioda.total_pe_num && >>> + !test_and_set_bit(pe, phb->ioda.pe_alloc)) >>> + break; >>> + >>> + if (--limit >= phb->ioda.total_pe_num) >>> return NULL; >>> - } while(test_and_set_bit(pe, phb->ioda.pe_alloc)); >>> + } while (1); >> >> >> Usually, if it is "while(1)", then it is "while(1){}" rather than >> "do{}while(1)" :) > > Agree, will change it. > >> >> >>> >>> return pnv_ioda_init_pe(phb, pe); >>> } >>> > > Thanks, > Gavin > -- Alexey