RE: [PATCH] PCI: Mark NXP LS1088 to avoid bus reset bus

[Bharat Bhushan <bharat.bhushan@nxp.com>]

Hi Alex,

> -----Original Message-----
> From: Alex Williamson <alex.williamson@redhat.com>
> Sent: Friday, November 30, 2018 11:26 AM
> To: Bharat Bhushan <bharat.bhushan@nxp.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>; Bjorn Helgaas
> <helgaas@kernel.org>; linux-pci@vger.kernel.org; Linux Kernel Mailing List
> <linux-kernel@vger.kernel.org>; bharatb.yadav@gmail.com; David Daney
> <david.daney@cavium.com>; jglauber@cavium.com;
> mbroemme@libmpq.org; chrisrblake93@gmail.com
> 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@nxp.com> wrote:
> 
> > Hi,
> >
> > > -----Original Message-----
> > > From: Bjorn Helgaas <bhelgaas@google.com>
> > > Sent: Thursday, November 29, 2018 1:46 AM
> > > To: Bharat Bhushan <bharat.bhushan@nxp.com>
> > > Cc: alex.williamson@redhat.com; Bjorn Helgaas <helgaas@kernel.org>;
> > > linux- pci@vger.kernel.org; Linux Kernel Mailing List <linux-
> > > kernel@vger.kernel.org>; bharatb.yadav@gmail.com; David Daney
> > > <david.daney@cavium.com>; jglauber@cavium.com;
> mbroemme@libmpq.org;
> > > chrisrblake93@gmail.com
> > > 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@nxp.com> wrote:
> > >
> > > > > -----Original Message-----
> > > > > From: Alex Williamson <alex.williamson@redhat.com>
> > > > > Sent: Tuesday, November 27, 2018 9:39 PM
> > > > > To: Bjorn Helgaas <helgaas@kernel.org>
> > > > > Cc: Bharat Bhushan <bharat.bhushan@nxp.com>;
> > > > > linux-pci@vger.kernel.org; linux-kernel@vger.kernel.org;
> > > > > bharatb.yadav@gmail.com; David Daney
> <david.daney@cavium.com>;
> > > Jan
> > > > > Glauber <jglauber@cavium.com>; Maik Broemme
> > > <mbroemme@libmpq.org>;
> > > > > Chris Blake <chrisrblake93@gmail.com>
> > > > > Subject: Re: [PATCH] PCI: Mark NXP LS1088 to avoid bus reset bus
> > > > >
> > > > > On Tue, 27 Nov 2018 09:33:56 -0600 Bjorn Helgaas
> > > > > <helgaas@kernel.org> 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


> 
> 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.

Thanks
-Bharat

> 
> Alex
> 
> > 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
> >
> > Thanks
> > -Bharat
> >
> >