From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f54.google.com ([209.85.220.54]:36109 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751917AbbHJOjJ (ORCPT ); Mon, 10 Aug 2015 10:39:09 -0400 Received: by pacrr5 with SMTP id rr5so105201963pac.3 for ; Mon, 10 Aug 2015 07:39:09 -0700 (PDT) Subject: Re: [PATCH v6 18/42] powerpc/powernv: Allocate PE# in deasending order To: Gavin Shan , linuxppc-dev@lists.ozlabs.org References: <1438834307-26960-1-git-send-email-gwshan@linux.vnet.ibm.com> <1438834307-26960-19-git-send-email-gwshan@linux.vnet.ibm.com> Cc: 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: <55C8B786.1050702@ozlabs.ru> Date: Tue, 11 Aug 2015 00:39:02 +1000 MIME-Version: 1.0 In-Reply-To: <1438834307-26960-19-git-send-email-gwshan@linux.vnet.ibm.com> Content-Type: text/plain; charset=koi8-r; format=flowed Sender: linux-pci-owner@vger.kernel.org List-ID: 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 ;) > 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? > > 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)" :) > > return pnv_ioda_init_pe(phb, pe); > } > -- Alexey