Subject: Re: [PATCH 0/6] Add the Mobiveil EP and Layerscape Gen4 EP driver support

From: Bjorn Helgaas <[email-masked]>
Date: Wed, 2 Oct 2019 16:14:21 -0500

On Tue, Sep 24, 2019 at 04:52:23PM +0100, Russell King - ARM Linux admin wrote:
> On Tue, Sep 24, 2019 at 03:18:47PM +0100, Russell King - ARM Linux admin wrote:
> > On Mon, Sep 16, 2019 at 10:17:36AM +0800, Xiaowei Bao wrote:
> > > This patch set are for adding Mobiveil EP driver and adding PCIe Gen4
> > > EP driver of NXP Layerscape platform.
> > > 
> > > This patch set depends on:
> > > https://patchwork.kernel.org/project/linux-pci/list/?series=159139
> > > 
> > > Xiaowei Bao (6):
> > >   PCI: mobiveil: Add the EP driver support
> > >   dt-bindings: Add DT binding for PCIE GEN4 EP of the layerscape
> > >   PCI: mobiveil: Add PCIe Gen4 EP driver for NXP Layerscape SoCs
> > >   PCI: mobiveil: Add workaround for unsupported request error
> > >   arm64: dts: lx2160a: Add PCIe EP node
> > >   misc: pci_endpoint_test: Add the layerscape PCIe GEN4 EP device
> > >     support
> > > 
> > >  .../bindings/pci/layerscape-pcie-gen4.txt          |  28 +-
> > >  MAINTAINERS                                        |   3 +
> > >  arch/arm64/boot/dts/freescale/fsl-lx2160a.dtsi     |  56 ++
> > >  drivers/misc/pci_endpoint_test.c                   |   2 +
> > >  drivers/pci/controller/mobiveil/Kconfig            |  22 +-
> > >  drivers/pci/controller/mobiveil/Makefile           |   2 +
> > >  .../controller/mobiveil/pcie-layerscape-gen4-ep.c  | 169 ++++++
> > >  drivers/pci/controller/mobiveil/pcie-mobiveil-ep.c | 568 +++++++++++++++++++++
> > >  drivers/pci/controller/mobiveil/pcie-mobiveil.c    |  99 +++-
> > >  drivers/pci/controller/mobiveil/pcie-mobiveil.h    |  72 +++
> > >  10 files changed, 1009 insertions(+), 12 deletions(-)
> > >  create mode 100644 drivers/pci/controller/mobiveil/pcie-layerscape-gen4-ep.c
> > >  create mode 100644 drivers/pci/controller/mobiveil/pcie-mobiveil-ep.c
> > 
> > Hi,
> > 
> > I've applied "PCI: mobiveil: Fix the CPU base address setup in inbound
> > window" and your patch set to 5.3, which seems to be able to detect the
> > PCIe card I have plugged in:
> > 
> > layerscape-pcie-gen4 3800000.pcie: host bridge /soc/pcie@3800000 ranges:
> > layerscape-pcie-gen4 3800000.pcie:   MEM 0xa040000000..0xa07fffffff -> 0x40000000
> > layerscape-pcie-gen4 3800000.pcie: PCI host bridge to bus 0000:00
> > pci_bus 0000:00: root bus resource [bus 00-ff]
> > pci_bus 0000:00: root bus resource [mem 0xa040000000-0xa07fffffff] (bus address
> > [0x40000000-0x7fffffff])
> > pci 0000:00:00.0: [1957:8d90] type 01 class 0x060400
> > pci 0000:00:00.0: enabling Extended Tags
> > pci 0000:00:00.0: supports D1 D2
> > pci 0000:00:00.0: PME# supported from D0 D1 D2 D3hot D3cold
> > pci 0000:01:00.0: [15b3:6750] type 00 class 0x020000
> > pci 0000:01:00.0: reg 0x10: [mem 0xa040000000-0xa0400fffff 64bit]
> > pci 0000:01:00.0: reg 0x18: [mem 0xa040800000-0xa040ffffff 64bit pref]
> > pci 0000:01:00.0: reg 0x30: [mem 0xa041000000-0xa0410fffff pref]
> > pci 0000:00:00.0: up support 3 enabled 0
> > pci 0000:00:00.0: dn support 1 enabled 0
> > pci 0000:00:00.0: BAR 9: assigned [mem 0xa040000000-0xa0407fffff 64bit pref]
> > pci 0000:00:00.0: BAR 8: assigned [mem 0xa040800000-0xa0409fffff]
> > pci 0000:01:00.0: BAR 2: assigned [mem 0xa040000000-0xa0407fffff 64bit pref]
> > pci 0000:01:00.0: BAR 0: assigned [mem 0xa040800000-0xa0408fffff 64bit]
> > pci 0000:01:00.0: BAR 6: assigned [mem 0xa040900000-0xa0409fffff pref]
> > pci 0000:00:00.0: PCI bridge to [bus 01-ff]
> > pci 0000:00:00.0:   bridge window [mem 0xa040800000-0xa0409fffff]
> > pci 0000:00:00.0:   bridge window [mem 0xa040000000-0xa0407fffff 64bit pref]
> > pci 0000:00:00.0: Max Payload Size set to  256/ 256 (was  128), Max Read Rq  256pci 0000:01:00.0: Max Payload Size set to  256/ 256 (was  128), Max Read Rq  256pcieport 0000:00:00.0: PCIe capabilities: 0x13
> > pcieport 0000:00:00.0: init_service_irqs: -19
> > 
> > However, a bit later in the kernel boot, I get:
> > 
> > SError Interrupt on CPU1, code 0xbf000002 -- SError
> > CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.3.0+ #392
> > Hardware name: SolidRun LX2160A COM express type 7 module (DT)
> > pstate: 60400085 (nZCv daIf +PAN -UAO)
> > pc : pci_generic_config_read+0xb0/0xc0
> > lr : pci_generic_config_read+0x1c/0xc0
> > sp : ffffff8010f9baf0
> > x29: ffffff8010f9baf0 x28: ffffff8010d620a0
> > x27: ffffff8010d79000 x26: ffffff8010d62000
> > x25: ffffff8010cb06d4 x24: 0000000000000000
> > x23: ffffff8010e499b8 x22: ffffff8010f9bbaf
> > x21: 0000000000000000 x20: ffffffe2eda11800
> > x19: ffffff8010f62158 x18: ffffff8010bdede0
> > x17: ffffff8010bdede8 x16: ffffff8010b96970
> > x15: ffffffffffffffff x14: ffffffffff000000
> > x13: ffffffffffffffff x12: 0000000000000030
> > x11: 0101010101010101 x10: 7f7f7f7f7f7f7f7f
> > x9 : 2dff716475687163 x8 : ffffffffffffffff
> > x7 : fefefefefefefefe x6 : 0000000000000000
> > x5 : 0000000000000000 x4 : ffffff8010f9bb6c
> > x3 : 0000000000000001 x2 : 0000000000000003
> > x1 : 0000000000000000 x0 : 0000000000000000
> > Kernel panic - not syncing: Asynchronous SError Interrupt
> > CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.3.0+ #392
> > Hardware name: SolidRun LX2160A COM express type 7 module (DT)
> > Call trace:
> >  dump_backtrace+0x0/0x120
> >  show_stack+0x14/0x1c
> >  dump_stack+0x9c/0xc0
> >  panic+0x148/0x34c
> >  print_tainted+0x0/0xa8
> >  arm64_serror_panic+0x74/0x80
> >  do_serror+0x8c/0x13c
> >  el1_error+0xbc/0x160
> >  pci_generic_config_read+0xb0/0xc0
> >  pci_bus_read_config_byte+0x64/0x90
> >  pci_read_config_byte+0x40/0x48
> >  pci_assign_irq+0x34/0xc8
> >  pci_device_probe+0x28/0x148
> >  really_probe+0x1c4/0x2d0
> >  driver_probe_device+0x58/0xfc
> >  device_driver_attach+0x68/0x70
> >  __driver_attach+0x94/0xdc
> >  bus_for_each_dev+0x50/0xa0
> >  driver_attach+0x20/0x28
> >  bus_add_driver+0x14c/0x200
> >  driver_register+0x6c/0x124
> >  __pci_register_driver+0x48/0x50
> >  mlx4_init+0x154/0x180
> >  do_one_initcall+0x30/0x250
> >  kernel_init_freeable+0x23c/0x32c
> >  kernel_init+0x10/0xfc
> >  ret_from_fork+0x10/0x18
> > SMP: stopping secondary CPUs
> > Kernel Offset: disabled
> > CPU features: 0x0002,21006008
> > Memory Limit: none
> > 
> > and there it dies.  Any ideas?
> 
> The failing access seems to be:
> 
>         pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
> 
> for the Mellanox Ethernet card.  Presumably, being a PCIe ethernet
> card, it doesn't implement this register (just a guess), and aborts
> the PCI transaction, which is presumably triggering the above SError.

PCIe r5.0, sec 7.5.1.1.13, says Interrupt Pin is a read-only register,
so there shouldn't be an issue with reading it.

mobiveil_pcie_ops uses the generic pci_generic_config_read(), which
will perform a readb() in this case.  Could mobiveil be a bridge that
only supports 32-bit config accesses?

> Note that I've used this card with the Macchiatobin (Armada 8040)
> without issue.
> 
> -- 
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
> According to speedtest.net: 11.9Mbps down 500kbps up

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