From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Daney Subject: Re: [PATCH v3 2/2] PCI: Add support for Enhanced Allocation devices Date: Wed, 30 Sep 2015 16:01:19 -0700 Message-ID: <560C69BF.6000205@caviumnetworks.com> References: <1443485439-12081-1-git-send-email-ddaney.cavm@gmail.com> <1443485439-12081-3-git-send-email-ddaney.cavm@gmail.com> <20150929192737.GA2517@sean.stalley.intel.com> <560AF3D7.80908@gmail.com> <20150929224727.GB2517@sean.stalley.intel.com> <560B2470.9080100@caviumnetworks.com> <20150930225011.GA4244@sean.stalley.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150930225011.GA4244@sean.stalley.intel.com> Sender: linux-pci-owner@vger.kernel.org To: "Sean O. Stalley" Cc: David Daney , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Bjorn Helgaas , "Michael S. Tsirkin" , =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= , linux-api@vger.kernel.org, yinghai@kernel.org, rajatxjain@gmail.com, gong.chen@linux.intel.com, David Daney List-Id: linux-api@vger.kernel.org On 09/30/2015 03:50 PM, Sean O. Stalley wrote: > On Tue, Sep 29, 2015 at 04:53:20PM -0700, David Daney wrote: >> On 09/29/2015 03:47 PM, Sean O. Stalley wrote: >> [...] >>>>>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c >>>>>> index 6a9a111..7c60b16 100644 >>>>>> --- a/drivers/pci/pci.c >>>>>> +++ b/drivers/pci/pci.c >>>>>> @@ -2148,6 +2148,284 @@ void pci_pm_init(struct pci_dev *dev) >>>>>> } >>>>>> } >>>>>> >>>>>> +static unsigned long pci_ea_set_flags(struct pci_dev *dev, u8 prop) >>>>>> +{ >>>>>> + unsigned long flags = IORESOURCE_PCI_FIXED | IORESOURCE_SIZEALIGN; >>>>> >>>>> Why did you add the IORESOURCE_SIZEALIGN flag? EA allows for unaligned resources. >>>> >>>> pci_bus_assign_resources() fails causing the devices to be unusable >>>> if resource_alignment() returns zero. The easiest fix for this was >>>> to specify IORESOURCE_SIZEALIGN. >>>> >>>> An alternative would be to change the code in setup-bus.c so that >>>> for IORESOURCE_PCI_FIXED resources, it didn't barf. >>> >>> I would do this alternative, but with a IORESOURCE_PCI_EA flag. >>> >> >> I don't think we need IORESOURCE_PCI_EA. If a resource is tagged as >> IORESOURCE_PCI_FIXED that means that it cannot be changed, we >> shouldn't care why it is fixed (due to an EA capability for >> example). We just need to gracefully handle IORESOURCE_PCI_FIXED in >> the places where things currently go wrong. >> >> David Daney >> > > I agree that we need to make sure fixed things stay fixed, > regardless of if they are fixed by EA or something else. > > The question is: do we want to allow all fixed resources to be non-aligned, or just EA? The alignment should only be important if a new address is being calculated for a BAR or behind the bridge memory/io region. If the resource is fixed, I would almost say that "alignment" is an undefined concept. So, in the places were we need special treatment for IORESOURCE_PCI_FIXED, I would argue that we shouldn't be use the resource alignment information. David Daney > > -Sean >