From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f182.google.com ([209.85.216.182]:37191 "EHLO mail-qc0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753315Ab3HFNo0 (ORCPT ); Tue, 6 Aug 2013 09:44:26 -0400 Received: by mail-qc0-f182.google.com with SMTP id c11so201247qcv.27 for ; Tue, 06 Aug 2013 06:44:25 -0700 (PDT) Date: Tue, 6 Aug 2013 07:44:21 -0600 From: Bjorn Helgaas To: Wei Yang Cc: "linux-pci@vger.kernel.org" , Ram Pai , Gavin Shan , Yinghai Lu Subject: Re: [PATCH 4/4] PCI: fix the io resource alignment calculation in pbus_size_io() Message-ID: <20130806134421.GD31970@google.com> References: <1375435866-16332-1-git-send-email-weiyang@linux.vnet.ibm.com> <1375435866-16332-5-git-send-email-weiyang@linux.vnet.ibm.com> <20130806061924.GB10876@weiyang.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20130806061924.GB10876@weiyang.vnet.ibm.com> Sender: linux-pci-owner@vger.kernel.org List-ID: On Tue, Aug 06, 2013 at 02:19:24PM +0800, Wei Yang wrote: > On Mon, Aug 05, 2013 at 11:58:50AM -0600, Bjorn Helgaas wrote: > >[+cc Yinghai] > > > >On Fri, Aug 2, 2013 at 3:31 AM, Wei Yang wrote: > >> In commit 462d9303 ("PCI: Align P2P windows using pcibios_window_alignment()"), > >> it introduce a new method to calculate the window alignment of P2P bridge. > >> > >> When the io_window_1k is set, the calculation for the io resource alignment > >> is different from the original one. In the original logic before 462d9303, > >> the alignment is no bigger than 4K even the io_window_1k is set. The logic > >> introduced in 462d9303 will limit the alignment to 1k in this case. > >> > >> This patch fix this issue. > > > >Presumably this fixes a bug, but you don't say what it is. "different > >from the original" is not a description of a problem. You need > >something like "with the current code, we allocate the wrong window > >size in situation X, or we allocate a window with incorrect alignment > >in situation Y, etc." > > > > With current code, we allocate the wrong window size when upstream bridge > could be 1k aligned and one of the downstream port is 4k aligned. > > In this case, the "min_align" should be 4k. But the current code set > "min_align" to 1k. I would expect that we allocate a window with incorrect *alignment*, not incorrect size. If you include a dmesg log and lspci output and point out the problem, that will avoid a lot of confusion. Bjorn