From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from eu-smtp-delivery-211.mimecast.com ([146.101.78.211]:35418 "EHLO eu-smtp-delivery-211.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729283AbeG3PIF (ORCPT ); Mon, 30 Jul 2018 11:08:05 -0400 From: David Laight To: 'Lukas Wunner' , "Alex_Gagniuc@Dellteam.com" CC: "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? Date: Mon, 30 Jul 2018 13:28:14 +0000 Message-ID: <11e48a8d8e144259b4d0fb073c6899c7@AcuMS.aculab.com> 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> In-Reply-To: <20180728183130.GA21482@wunner.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-pci-owner@vger.kernel.org List-ID: 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. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)