Hi Alex, > -----Original Message----- > From: Alex Williamson <alex.williamson@xxxxxxxxxx> > Sent: Friday, November 30, 2018 9:49 PM > To: Bharat Bhushan <bharat.bhushan@xxxxxxx> > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; Bjorn Helgaas > <helgaas@xxxxxxxxxx>; linux-pci@xxxxxxxxxxxxxxx; Linux Kernel Mailing List > <linux-kernel@xxxxxxxxxxxxxxx>; bharatb.yadav@xxxxxxxxx; David Daney > <david.daney@xxxxxxxxxx>; jglauber@xxxxxxxxxx; > mbroemme@xxxxxxxxxx; chrisrblake93@xxxxxxxxx > Subject: Re: [PATCH] PCI: Mark NXP LS1088 to avoid bus reset bus > > On Fri, 30 Nov 2018 06:24:16 +0000 > Bharat Bhushan <bharat.bhushan@xxxxxxx> wrote: > > > Hi Alex, > > > > > -----Original Message----- > > > From: Alex Williamson <alex.williamson@xxxxxxxxxx> > > > Sent: Friday, November 30, 2018 11:26 AM > > > To: Bharat Bhushan <bharat.bhushan@xxxxxxx> > > > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; Bjorn Helgaas > > > <helgaas@xxxxxxxxxx>; linux-pci@xxxxxxxxxxxxxxx; Linux Kernel > > > Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; > > > bharatb.yadav@xxxxxxxxx; David Daney <david.daney@xxxxxxxxxx>; > > > jglauber@xxxxxxxxxx; mbroemme@xxxxxxxxxx; > chrisrblake93@xxxxxxxxx > > > Subject: Re: [PATCH] PCI: Mark NXP LS1088 to avoid bus reset bus > > > > > > On Fri, 30 Nov 2018 05:29:47 +0000 > > > Bharat Bhushan <bharat.bhushan@xxxxxxx> wrote: > > > > > > > Hi, > > > > > > > > > -----Original Message----- > > > > > From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > > > > > Sent: Thursday, November 29, 2018 1:46 AM > > > > > To: Bharat Bhushan <bharat.bhushan@xxxxxxx> > > > > > Cc: alex.williamson@xxxxxxxxxx; Bjorn Helgaas > > > > > <helgaas@xxxxxxxxxx>; > > > > > linux- pci@xxxxxxxxxxxxxxx; Linux Kernel Mailing List <linux- > > > > > kernel@xxxxxxxxxxxxxxx>; bharatb.yadav@xxxxxxxxx; David Daney > > > > > <david.daney@xxxxxxxxxx>; jglauber@xxxxxxxxxx; > > > mbroemme@xxxxxxxxxx; > > > > > chrisrblake93@xxxxxxxxx > > > > > Subject: Re: [PATCH] PCI: Mark NXP LS1088 to avoid bus reset bus > > > > > > > > > > On Tue, Nov 27, 2018 at 10:32 PM Bharat Bhushan > > > > > <bharat.bhushan@xxxxxxx> wrote: > > > > > > > > > > > > -----Original Message----- > > > > > > > From: Alex Williamson <alex.williamson@xxxxxxxxxx> > > > > > > > Sent: Tuesday, November 27, 2018 9:39 PM > > > > > > > To: Bjorn Helgaas <helgaas@xxxxxxxxxx> > > > > > > > Cc: Bharat Bhushan <bharat.bhushan@xxxxxxx>; > > > > > > > linux-pci@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > > > > > > > bharatb.yadav@xxxxxxxxx; David Daney > > > <david.daney@xxxxxxxxxx>; > > > > > Jan > > > > > > > Glauber <jglauber@xxxxxxxxxx>; Maik Broemme > > > > > <mbroemme@xxxxxxxxxx>; > > > > > > > Chris Blake <chrisrblake93@xxxxxxxxx> > > > > > > > Subject: Re: [PATCH] PCI: Mark NXP LS1088 to avoid bus reset > > > > > > > bus > > > > > > > > > > > > > > On Tue, 27 Nov 2018 09:33:56 -0600 Bjorn Helgaas > > > > > > > <helgaas@xxxxxxxxxx> wrote: > > > > > > > > > > > > > 4) Is there a hardware erratum for this? If so, please > > > > > > > > include the URL here. > > > > > > > > > > > > No h/w errata as of now. > > > > > > > > > > Does that mean (a) the HW folks agree this is a hardware problem > > > > > but they haven't written an erratum, (b) there is an erratum but > > > > > it isn't public, (c) we don't have any concrete evidence of a > > > > > hardware problem, but things just don't work if we do a bus > > > > > reset, (d) something > > > else? > > > > > > > > I will say it is (c) - not concluded to be hardware h/w issue. > > > > > > > > > > > > > > > In pci_reset_secondary_bus() I have tried to increase the > > > > > > delay after reset > > > > > but not helped. > > > > > > Do I need to add delay at some other place as well? > > > > > > > > > > No, I think the place you tried should be enough. > > > > > > > > > > You should also be able to exercise this from user-space by > > > > > using "setpci" to set and clear the Secondary Bus Reset bit in > > > > > the Bridge Control register. Then you can also use setpci to > > > > > read/write config space of the NIC. The kernel would normally > > > > > read the Vendor and Device IDs as the first access to the device > during enumeration. > > > > > You also might be able to learn something by using "lspci -vv" > > > > > on the bridge before and after the reset to see if it logs any > > > > > AER bits (if it > > > supports AER) or the other standard error logging bits. > > > > > > > > I tried below sequence for Secondary bus reset and device config > > > > space show 0xff > > > > > > > > root@localhost:~# lspci -x > > > > 0002:00:00.0 PCI bridge: Freescale Semiconductor Inc Device 80c0 > > > > (rev > > > > 10) > > > > 00: 57 19 c0 80 07 01 10 00 10 00 04 06 08 00 01 00 > > > > 10: 00 00 00 00 00 00 00 00 00 01 ff 00 01 01 00 00 > > > > 20: 00 40 00 40 f1 ff 01 00 00 00 00 00 00 00 00 00 > > > > 30: 00 00 00 00 40 00 00 00 00 00 00 40 63 01 00 00 > > > > > > > > 0002:01:00.0 Ethernet controller: Intel Corporation 82574L Gigabit > > > > Network Connection > > > > 00: 86 80 d3 10 06 04 10 00 00 00 00 02 10 00 00 00 > > > > 10: 00 00 0c 40 00 00 00 40 01 00 00 00 00 00 0e 40 > > > > 20: 00 00 00 00 00 00 00 00 00 00 00 00 86 80 1f a0 > > > > 30: 00 00 24 40 c8 00 00 00 00 00 00 00 63 01 00 00 > > > > > > > > root@localhost:~# setpci -s 0002:00:00.0 0x3e.b=0x40 > > > > root@localhost:~# setpci -s 0002:00:00.0 0x3e.b=0x00 > > > > > > > > root@localhost:~# lspci -x > > > > 0002:00:00.0 PCI bridge: Freescale Semiconductor Inc Device 80c0 > > > > (rev > > > > 10) > > > > 00: 57 19 c0 80 07 01 10 00 10 00 04 06 08 00 01 00 > > > > 10: 00 00 00 00 00 00 00 00 00 01 ff 00 01 01 00 00 > > > > 20: 00 40 00 40 f1 ff 01 00 00 00 00 00 00 00 00 00 > > > > 30: 00 00 00 00 40 00 00 00 00 00 00 40 63 01 00 00 > > > > > > Just for curiosity sake, what if you re-write the secondary and > > > subordinate bus registers here: > > > > > > # setpci -s 0002:00:00.0 0x19.b=0x01 # setpci -s 0002:00:00.0 > > > 0x1a.b=0xff > > > > Result is same, here are logs > > > > root@localhost:~# setpci -s 0002:00:00.0 0x3e.b=0x40 root@localhost:~# > > setpci -s 0002:00:00.0 0x3e.b=0x00 root@localhost:~# setpci -s > > 0002:00:00.0 0x19.b=0x01 root@localhost:~# setpci -s 0002:00:00.0 > > 0x1a.b=0xff root@localhost:~# lspci -x > > 0002:00:00.0 PCI bridge: Freescale Semiconductor Inc Device 80c0 (rev > > 10) > > 00: 57 19 c0 80 07 01 10 00 10 00 04 06 08 00 01 00 > > 10: 00 00 00 00 00 00 00 00 00 01 ff 00 01 01 00 00 > > 20: 00 40 00 40 f1 ff 01 00 00 00 00 00 00 00 00 00 > > 30: 00 00 00 00 40 00 00 00 00 00 00 40 63 01 00 00 > > > > 0002:01:00.0 Ethernet controller: Intel Corporation 82574L Gigabit > > Network Connection (rev ff) > > 00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > > 10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > > 20: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > > 30: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff > > Ok, thanks for scratching my itch. > > > > IIRC the users that debugged the AMD bus reset issue re-wrote the > > > entire 64 bytes of the bridge config header and then further > > > narrowed the issue down to the two registers above. If one bridge > > > implementation can have such an issue, maybe others do too. Perhaps > there's common IP in use. > > > > > Are you able > > > to test other endpoints besides this e1000e device with this setpci > > > technique? Thanks, > > > > I tried with " Broadcom Limited NetXtreme BCM5722 Gigabit Ethernet PCI > Express" I observe same issue. > > Personally I'd exhaust talking with your hardware folks before blocking bus > resets at the software level, it seems like a gap in PCIe compliance of the > device. Thanks, I will continue to work with our h/w team on this. Thanks -Bharat > > Alex
