From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bmailout1.hostsharing.net ([83.223.95.100]:54783 "EHLO bmailout1.hostsharing.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726530AbeG3P3a (ORCPT ); Mon, 30 Jul 2018 11:29:30 -0400 Date: Mon, 30 Jul 2018 15:54:21 +0200 From: Lukas Wunner To: David Laight Cc: "Alex_Gagniuc@Dellteam.com" , "mr.nuke.me@gmail.com" , "keith.busch@intel.com" , "linux-pci@vger.kernel.org" , "Austin.Bolen@dell.com" , "Stuart.Hayes@dell.com" , "Narendra.K@dell.com" , "Christopher.Arzola@dell.com" , "David.Chalfant@dell.com" , Sinan Kaya Subject: Re: Should a PCIe Link Down event set the PCI_DEV_DISCONNECTED bit? Message-ID: <20180730135421.GA2680@wunner.de> References: <47727551-86ce-040a-2516-efa47ee3a76e@gmail.com> <20180727071813.GA6128@wunner.de> <20180727170543.GA5326@wunner.de> <99604d46a7554eb38ee6c1579c53d835@ausx13mps321.AMER.DELL.COM> <20180728183130.GA21482@wunner.de> <11e48a8d8e144259b4d0fb073c6899c7@AcuMS.aculab.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <11e48a8d8e144259b4d0fb073c6899c7@AcuMS.aculab.com> Sender: linux-pci-owner@vger.kernel.org List-ID: On Mon, Jul 30, 2018 at 01:28:14PM +0000, David Laight wrote: > From: Lukas Wunner > > Sent: 28 July 2018 19:32 > ... > > Finally, if the card was quickly swapped and the link to the new > > card is already up, you may be accessing that new card. (mmio > > accesses may then still return all ones if the BARs are blank, > > but at least config space accesses should work.) > > On my i7-7700 system that no longer works (at least with some cards). > If I take the PCIe link down completely (reset the FPGA on the card) > it doesn't recover (loops through detect active/quiet and a third > state I can't quite remember). > > ISTR that it recovers from the link going down when I short out > the PCIe data lines. > > It worked fine on a XEON E5-2609 system - I did it a lot when > updating the fpga image. > > Can anyone else verify whether this works on other systems? > Or whether the kernel (or BIOS) needs to (re-)initialise > some register to make link recovery work. Huh? Can you be a bit more specific what exactly no longer works and which branch or kernel version introduced the regression? Thanks, Lukas