[RFT PATCH v2 00/42] PCI: ARM/ARM64: remove pci_fixup_irqs() usage

[Lorenzo Pieralisi]

On Wed, Jun 21, 2017 at 10:39:31AM +0200, Linus Walleij wrote:
> On Thu, Jun 8, 2017 at 4:13 PM, Lorenzo Pieralisi
> <lorenzo.pieralisi at arm.com> wrote:
> 
> I pulled this into the Gemini tree:
> > [1] git://git.kernel.org/pub/scm/linux/kernel/git/lpieralisi/linux.git pci/pci-fixup-irqs-removal-v2
> 

Thank you Linus for helping me out.

> And then this happens:
> 
> OF: PCI: host bridge /soc/pci at 50000000 ranges:
> OF: PCI:    IO 0x50000000..0x500fffff -> 0x00000000
> OF: PCI:   MEM 0x58000000..0x5fffffff -> 0x58000000
> Unable to handle kernel NULL pointer dereference at virtual address 00000070
> pgd = c0004000
> [00000070] *pgd=00000000
> Internal error: Oops: 17 [#1] PREEMPT ARM
> CPU: 0 PID: 254 Comm: kworker/0:1 Not tainted 4.12.0-rc3+ #888
> Hardware name: Gemini (Device Tree)
> Workqueue: events deferred_probe_work_func
> task: c38c3a40 task.stack: c390a000
> PC is at faraday_pci_probe+0x274/0x65c
> LR is at __irq_put_desc_unlock+0x18/0x70
> pc : [<c0232648>]    lr : [<c004be48>]    psr: 80000013

I think I see what it is. faraday_pci_irq_handler() relies on
struct faraday_pci->bus to access config space and with this
series it can't be set till pci_scan_root_bus_bridge() returns.

If that's the case we will have to update the config accessors in
faraday_pci_irq_handler() to raw ones (ie ones that do not depend on the
struct pci_bus), code is already there, patch coming, sorry about this
but it is extremely complicated for me to untangle these drivers inner
workings.

Thanks,
Lorenzo

> sp : c390bdf0  ip : c3424274  fp : c3ac2ee0
> r10: c3f77718  r9 : c3ad49b0  r8 : c3907800
> r7 : 00000004  r6 : c390be18  r5 : c3907810  r4 : c3ad4810
> r3 : 00000000  r2 : 00000000  r1 : 00000001  r0 : c3ac2de0
> Flags: Nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
> Control: 0000397f  Table: 03a9c000  DAC: 00000053
> Process kworker/0:1 (pid: 254, stack limit = 0xc390a190)
> Stack: (0xc390bdf0 to 0xc390c000)
> bde0:                                     c0534a60 c3ad49b0 00000003 c024cb68
> be00: 00000001 20000013 00000000 50000000 00000007 000020dd c3ae2680 c3ae2740
> be20: c07c861f c0134328 00000000 c3ad5fa0 c3910a50 c3910a50 00000001 00000000
> be40: 00000000 c01344ec c3910a50 c3910a50 00000001 00000000 c3910a50 c39d76e0
> be60: c3ad5fa0 c05f6f58 c3910a50 c3907810 c3907810 c07cba88 fffffdfb 00000003
> be80: 00000000 c07c5040 c386e420 c02bbbe0 c3907810 c081c6c4 00000000 c07cba88
> bea0: 00000003 c02ba9dc 00000000 c390bee0 c02bab30 00000001 c07bf660 00000000
> bec0: c07c5040 c02b93dc c382829c c39886f4 c3907810 c3907844 c3907810 c02ba674
> bee0: c3907810 00000001 c390bf0c c3907810 c07d3a80 c3907810 c07d38e4 c02b961c
> bf00: c3907810 c07d38d0 c07d38d0 c02ba210 c07d38ec c386e420 00000000 c3f6b100
> bf20: c07bf660 c002dac0 00000008 c07bf660 c07bf660 c386e438 c390a000 c07bf674
> bf40: 00000008 c07bf660 c07c5040 c002e044 c390a000 00000001 00000000 00000000
> bf60: c3901518 c3901500 ffffe000 c38e2700 00000000 c3901518 c386e420 c002ddb4
> bf80: c3839ee4 c00335ec c390a000 c38e2700 c003350c 00000000 00000000 00000000
> bfa0: 00000000 00000000 00000000 c000a270 00000000 00000000 00000000 00000000
> bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> bfe0: 00000000 00000000 00000000 00000000 00000013 00000000 ffffffff ffffffff
> [<c0232648>] (faraday_pci_probe) from [<c02bbbe0>]
> (platform_drv_probe+0x50/0xb4)
> [<c02bbbe0>] (platform_drv_probe) from [<c02ba9dc>]
> (driver_probe_device+0x248/0x2dc)
> [<c02ba9dc>] (driver_probe_device) from [<c02b93dc>]
> (bus_for_each_drv+0x68/0x98)
> [<c02b93dc>] (bus_for_each_drv) from [<c02ba674>] (__device_attach+0xa8/0x110)
> [<c02ba674>] (__device_attach) from [<c02b961c>] (bus_probe_device+0x88/0x90)
> [<c02b961c>] (bus_probe_device) from [<c02ba210>]
> (deferred_probe_work_func+0x54/0x80)
> [<c02ba210>] (deferred_probe_work_func) from [<c002dac0>]
> (process_one_work+0x13c/0x430)
> [<c002dac0>] (process_one_work) from [<c002e044>] (worker_thread+0x290/0x5f4)
> [<c002e044>] (worker_thread) from [<c00335ec>] (kthread+0xe0/0x120)
> [<c00335ec>] (kthread) from [<c000a270>] (ret_from_fork+0x14/0x24)
> Code: e59401b0 e3700a01 8a00001d e59421ac (e5d23070)
> ---[ end trace 1e313b1ea11e101c ]---
> 
> I'm trying to figure out what is causing it.
> 
> Yours,
> Linus Walleij