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Message-ID: <54FE30B6.3070400@broadcom.com>
Date: Mon, 9 Mar 2015 16:45:58 -0700
From: Ray Jui <rjui@...adcom.com>
To: Arnd Bergmann <arnd@...db.de>
CC: Dmitry Torokhov <dtor@...gle.com>, Paul Bolle <pebolle@...cali.nl>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Hauke Mehrtens <hauke@...ke-m.de>,
Florian Fainelli <f.fainelli@...il.com>,
Anatol Pomazau <anatol@...gle.com>,
Scott Branden <sbranden@...adcom.com>,
<linux-pci@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<bcm-kernel-feedback-list@...adcom.com>,
<devicetree@...r.kernel.org>
Subject: Re: [PATCH v3 2/3] pci: iproc: Add Broadcom iProc PCIe support
Hi Arnd,
On 3/9/2015 5:35 AM, Arnd Bergmann wrote:
> On Friday 06 March 2015 10:00:34 Ray Jui wrote:
>>>
>>
>> Although I have not tested it, but to my best knowledge there shouldn't
>> be any technical issue by making the PCIe iProc driver a loadable module
>> and installing the module later after the kernel finishes booting.
>>
>> But I wonder why I haven't seen any PCIe host driver being allowed to be
>> compiled as module? Maybe there's no obvious benefit of doing that.
>> People typically opt to load slave devices as module but tend to keep
>> the bus or host devices compiled in.
>>
>> And to allow a PCI host driver to be compiled as module, some PCI
>> functions need to have their symbols exported:
>>
>> ERROR: "pci_common_swizzle" [drivers/pci/host/pcie-iproc.ko] undefined!
>> ERROR: "pci_fixup_irqs" [drivers/pci/host/pcie-iproc.ko] undefined!
>> ERROR: "pci_assign_unassigned_bus_resources"
>> [drivers/pci/host/pcie-iproc.ko] undefined!
>> ERROR: "pci_remove_root_bus" [drivers/pci/host/pcie-iproc.ko] undefined!
>> ERROR: "pci_stop_root_bus" [drivers/pci/host/pcie-iproc.ko] undefined!
>> ERROR: "pci_create_root_bus" [drivers/pci/host/pcie-iproc.ko] undefined!
>>
>> Maybe Bjorn can help to shed some light here? Should I go ahead and
>> export_symbol these PCI functions and make the iProc PCI driver "tristate"?
>
> My best guess is that no loadable driver ever tried to use these and
> we should indeed just export them.
True. I can export those symbols.
>
> The call to pci_assign_unassigned_bus_resources could be avoided by using
> pci_rescan_bus(), which would simplify the driver a little, but for
> some reason, nothing else uses that, so I'm not sure about it.
>
> The pci_remove_root_bus/pci_stop_root_bus calls are rarely used anywhere
> else. Are they functional to the point where you could unload a pci
> host driver that is a loadable module? If so, that would be
> wonderful.
It is quite wonderful, :)
I added driver remove function support and tested it out. I'm able to
install/remove/install the iProc PCIe platform driver as a kernel
loadable module. pci_remove_root_bus/pci_stop_root_bus works fine. See
logs below.
-bash-3.2# insmod pcie-iproc-pltfm.ko
[ 54.058546] PCI host bridge /pcie@...12000 ranges:
[ 54.064584] IO 0x28000000..0x2800ffff -> 0x00000000
[ 54.071003] MEM 0x20000000..0x23ffffff -> 0x20000000
[ 54.330194] iproc-pcie 18012000.pcie: PCI host bridge to bus 0000:00
[ 54.338138] pci_bus 0000:00: root bus resource [bus 00-ff]
[ 54.344983] pci_bus 0000:00: root bus resource [io 0x0000-0xffff]
[ 54.352683] pci_bus 0000:00: root bus resource [mem
0x20000000-0x23ffffff]
[ 54.361254] iproc-pcie 18012000.pcie: link: UP
[ 54.367086] PCI: bus0: Fast back to back transfers disabled
[ 54.374046] pci 0000:00:00.0: bridge configuration invalid ([bus
00-00]), reconfiguring
[ 54.400237] PCI: bus1: Fast back to back transfers disabled
[ 54.407274] pci 0000:00:00.0: BAR 8: assigned [mem 0x20000000-0x200fffff]
[ 54.415766] pci 0000:01:00.0: BAR 1: assigned [mem 0x20000000-0x2007ffff]
[ 54.424241] pci 0000:01:00.0: BAR 6: assigned [mem
0x20080000-0x200bffff pref]
[ 54.433245] pci 0000:01:00.0: BAR 0: assigned [mem 0x200c0000-0x200dffff]
[ 54.441710] pci 0000:01:00.0: BAR 3: assigned [mem 0x200e0000-0x200e3fff]
[ 54.450173] pci 0000:01:00.0: BAR 2: no space for [io size 0x0020]
[ 54.457979] pci 0000:01:00.0: BAR 2: failed to assign [io size 0x0020]
[ 54.466217] pci 0000:00:00.0: PCI bridge to [bus 01]
[ 54.472404] pci 0000:00:00.0: bridge window [mem 0x20000000-0x200fffff]
[ 54.480945] pcieport 0000:00:00.0: enabling device (0140 -> 0142)
[ 54.488767] e1000e 0000:01:00.0: enabling device (0140 -> 0142)
[ 54.496315] e1000e 0000:01:00.0: Interrupt Throttling Rate (ints/sec)
set to dynamic conservative mode
[ 54.507958] e1000e 0000:01:00.0 0000:01:00.0 (uninitialized): Failed
to initialize MSI-X interrupts. Falling back to MSI interru.
[ 54.522913] e1000e 0000:01:00.0 0000:01:00.0 (uninitialized): Failed
to initialize MSI interrupts. Falling back to legacy interr.
[ 54.643486] e1000e 0000:01:00.0 eth0: registered PHC clock
[ 54.650379] e1000e 0000:01:00.0 eth0: (PCI Express:2.5GT/s:Width x1)
68:05:ca:28:19:e8
[ 54.660254] e1000e 0000:01:00.0 eth0: Intel(R) PRO/1000 Network
Connection
[ 54.668834] e1000e 0000:01:00.0 eth0: MAC: 3, PHY: 8, PBA No: E46981-008
-bash-3.2# rmmod pcie-iproc-pltfm
[ 66.465834] e1000e 0000:01:00.0 eth0: removed PHC
-bash-3.2# insmod pcie-iproc-pltfm.ko
[ 71.043195] PCI host bridge /pcie@...12000 ranges:
[ 71.049235] IO 0x28000000..0x2800ffff -> 0x00000000
[ 71.055652] MEM 0x20000000..0x23ffffff -> 0x20000000
[ 71.315192] iproc-pcie 18012000.pcie: PCI host bridge to bus 0000:00
[ 71.323135] pci_bus 0000:00: root bus resource [bus 00-ff]
[ 71.329979] pci_bus 0000:00: root bus resource [io 0x0000-0xffff]
[ 71.337679] pci_bus 0000:00: root bus resource [mem
0x20000000-0x23ffffff]
[ 71.346249] iproc-pcie 18012000.pcie: link: UP
[ 71.352072] PCI: bus0: Fast back to back transfers disabled
[ 71.375261] PCI: bus1: Fast back to back transfers disabled
[ 71.382291] pci 0000:00:00.0: BAR 8: assigned [mem 0x20000000-0x200fffff]
[ 71.390782] pci 0000:01:00.0: BAR 1: assigned [mem 0x20000000-0x2007ffff]
[ 71.399258] pci 0000:01:00.0: BAR 6: assigned [mem
0x20080000-0x200bffff pref]
[ 71.408263] pci 0000:01:00.0: BAR 0: assigned [mem 0x200c0000-0x200dffff]
[ 71.416728] pci 0000:01:00.0: BAR 3: assigned [mem 0x200e0000-0x200e3fff]
[ 71.425190] pci 0000:01:00.0: BAR 2: no space for [io size 0x0020]
[ 71.432996] pci 0000:01:00.0: BAR 2: failed to assign [io size 0x0020]
[ 71.441235] pci 0000:00:00.0: PCI bridge to [bus 01]
[ 71.447422] pci 0000:00:00.0: bridge window [mem 0x20000000-0x200fffff]
[ 71.456125] pcieport 0000:00:00.0: Signaling PME through PCIe PME
interrupt
[ 71.464812] pci 0000:01:00.0: Signaling PME through PCIe PME interrupt
[ 71.473411] e1000e 0000:01:00.0: Interrupt Throttling Rate (ints/sec)
set to dynamic conservative mode
[ 71.485069] e1000e 0000:01:00.0 0000:01:00.0 (uninitialized): Failed
to initialize MSI-X interrupts. Falling back to MSI interru.
[ 71.500025] e1000e 0000:01:00.0 0000:01:00.0 (uninitialized): Failed
to initialize MSI interrupts. Falling back to legacy interr.
[ 71.624549] e1000e 0000:01:00.0 eth0: registered PHC clock
[ 71.631444] e1000e 0000:01:00.0 eth0: (PCI Express:2.5GT/s:Width x1)
68:05:ca:28:19:e8
[ 71.641314] e1000e 0000:01:00.0 eth0: Intel(R) PRO/1000 Network
Connection
[ 71.649894] e1000e 0000:01:00.0 eth0: MAC: 3, PHY: 8, PBA No: E46981-008
>
> Arnd
>
I'll submit patch series v4 with loadable module support.
Thanks,
Ray
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