From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Subject: Re: [PATCH V3 5/6] Avoid duplicate probe for of platform devices Date: Mon, 09 Jul 2012 08:58:11 -0500 Message-ID: <4FFAE373.6070905@gmail.com> References: <1339148585-16947-1-git-send-email-B38951@freescale.com> <4FD60FB1.7050106@gmail.com> <412C8208B4A0464FA894C5F0C278CD5D01A16829@039-SN1MPN1-002.039d.mgd.msft.net> <20120706042611.GA1841@kroah.com> <412C8208B4A0464FA894C5F0C278CD5D01A168F2@039-SN1MPN1-002.039d.mgd.msft.net> <20120706161718.GA26894@kroah.com> <412C8208B4A0464FA894C5F0C278CD5D01A1E694@039-SN1MPN1-002.039d.mgd.msft.net> <94F013E7935FF44C83EBE7784D62AD3F09354AE6@039-SN2MPN1-021.039d.mgd.msft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <94F013E7935FF44C83EBE7784D62AD3F09354AE6@039-SN2MPN1-021.039d.mgd.msft.net> Sender: linux-kernel-owner@vger.kernel.org To: Li Yang-R58472 Cc: Jia Hongtao-B38951 , Greg KH , "devicetree-discuss@lists.ozlabs.org" , "linux-kernel@vger.kernel.org" List-Id: devicetree@vger.kernel.org On 07/08/2012 10:46 PM, Li Yang-R58472 wrote: >>> I don't understand, why is this just showing up now? What >>> changed to cause this? Couldn't that be the real problem here? >>> >> >> The issue is showing up because we now probe devices twice. >> Previously, we just probe devices once. But now we changed the way >> of pci init which makes pci controllers should be probed earlier >> than other devices. So we have to probe pci nodes separately. Probe >> more than once is the root cause of this issue. >> >> The pci patchset I mentioned please refer to: >> http://patchwork.ozlabs.org/patch/163742/ > > Let me try to clarify a little bit. The of platform bus normally > traverse the device tree to add all the devices. The change which > caused problem is that we need to probe PCIe RC devices at a earlier > stage of initialization. So we added these PCIe RC devices earlier > than the normal device tree traversal process. These PCIe RC devices > will be scanned again during the normal traversal and cause > duplicated devices being added. Our proposal is to deal with > duplicated devices automatically and make it possible to scan the > device tree multiple times for devices to be added. What is making PCI need to be probed earlier? Perhaps deferred probe would work? Perhaps giving of_platform_populate an exclude list of compatible strings to skip would work. Rob