[PATCH v4 5/6] pci: Use parent domain number when allocating child busses.
Liviu Dudau
liviu at dudau.co.uk
Mon Mar 3 20:53:32 EST 2014
On Mon, Mar 03, 2014 at 05:42:04PM -0800, Tanmay Inamdar wrote:
> Hi Liviu,
>
> Actually your suggested implementation of pci_domain_nr is working
> perfectly. My bad for earlier email. I did not implement it correctly.
Great. I will send an updated series for arm64 tomorrow.
Best regards,
Liviu
>
> Thanks,
> Tanmay
>
> On Mon, Mar 3, 2014 at 4:42 PM, Tanmay Inamdar <tinamdar at apm.com> wrote:
> > Hello,
> >
> > Please see inline.
> >
> > On Mon, Mar 3, 2014 at 3:51 PM, Liviu Dudau <liviu at dudau.co.uk> wrote:
> >> On Mon, Mar 03, 2014 at 03:14:47PM -0800, Tanmay Inamdar wrote:
> >>> Hello Liviu,
> >>>
> >>> Thanks for fixing up domain_nr. Now I have moved on further to a new
> >>> domain_nr related warning dump :-)
> >>>
> >>> -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> >>> xgene-pcie 1f500000.pcie: (rc) x8 gen-3 link up
> >>> pci_bus 0001:00: scanning bus
> >>> pci_setup_device:1101 domain_nr = 1
> >>> pci 0001:00:00.0: [e008:e004] type 01 class 0x060400
> >>> pci 0001:00:00.0: reg 0x10: [mem 0x4000000000-0x7fffffffff 64bit]
> >>> pci 0001:00:00.0: calling xgene_pcie_fixup_bridge+0x0/0x80
> >>> pci 0001:00:00.0: Hiding X-Gene pci host bridge resources 0001:00:00.0
> >>> pci 0001:00:00.0: supports D1 D2
> >>> pci_bus 0001:00: fixups for bus
> >>> pci 0001:00:00.0: scanning [bus 03-03] behind bridge, pass 0
> >>> pci 0001:00:00.0: bridge configuration invalid ([bus 03-03]), reconfiguring
> >>> pci 0001:00:00.0: scanning [bus 00-00] behind bridge, pass 1
> >>> ** pci_scan_bridge:855 pci_domain_nr(bus) = 1
> >>> ** pci_alloc_child_bus:681 pci_domain_nr(bus) = 1
> >>> pci_bus 0001:01: scanning bus
> >>> pci_setup_device:1101 domain_nr = 0
> >>
> >> Why does the domain_nr change here?
> >
> > The bridge device pointer for parent and child should be same right? I
> > think this is not the case here. Please look at the log at the bottom
> > that I captured after trying your suggestions.
> >
> >>
> >>> pci 0000:01:00.0: [15b3:1003] type 00 class 0x020000
> >>> pci 0000:01:00.0: reg 0x10: [mem 0x00100000-0x001fffff 64bit]
> >>> pci 0000:01:00.0: reg 0x18: [mem 0x00800000-0x00ffffff 64bit pref]
> >>> pci 0000:01:00.0: reg 0x30: [mem 0x01000000-0x010fffff pref]
> >>> ------------[ cut here ]------------
> >>> WARNING: CPU: 0 PID: 1 at
> >>> /home/tinamdar/work/open-source/linux/fs/sysfs/dir.c:52
> >>> sysfs_warn_dup+0x80/0xc0()
> >>> sysfs: cannot create duplicate filename '/bus/pci/devices/0000:01:00.0'
> >>> Modules linked in:
> >>> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.0-rc5+ #40
> >>> Call trace:
> >>> [<ffffffc000088180>] dump_backtrace+0x0/0x140
> >>> [<ffffffc0000882d0>] show_stack+0x10/0x20
> >>> [<ffffffc0004f65ac>] dump_stack+0x74/0xc4
> >>> [<ffffffc000096e04>] warn_slowpath_common+0x84/0xc0
> >>> [<ffffffc000096e8c>] warn_slowpath_fmt+0x4c/0x60
> >>> [<ffffffc0001b83dc>] sysfs_warn_dup+0x7c/0xc0
> >>> [<ffffffc0001b8894>] sysfs_do_create_link_sd.isra.2+0xf4/0x100
> >>> [<ffffffc0001b88bc>] sysfs_create_link+0x1c/0x40
> >>> [<ffffffc0003250b0>] bus_add_device+0x110/0x1c0
> >>> [<ffffffc000322f1c>] device_add+0x31c/0x520
> >>> [<ffffffc0002c444c>] pci_device_add+0xec/0x140
> >>> [<ffffffc0004f1758>] pci_scan_single_device+0x98/0xe0
> >>> [<ffffffc0002c44e8>] pci_scan_slot+0x48/0x120
> >>> [<ffffffc0002c5368>] pci_scan_child_bus+0x48/0x140
> >>> [<ffffffc0002c522c>] pci_scan_bridge+0x4ec/0x5e0
> >>> [<ffffffc0002c53c8>] pci_scan_child_bus+0xa8/0x140
> >>> [<ffffffc0004f1b30>] pci_rescan_bus+0x10/0x40
> >>> [<ffffffc0006a12ac>] xgene_pcie_probe_bridge+0x660/0x72c
> >>> [<ffffffc000327d20>] platform_drv_probe+0x20/0x60
> >>> [<ffffffc000325e30>] really_probe+0xf0/0x220
> >>> [<ffffffc000326080>] __driver_attach+0xa0/0xc0
> >>> [<ffffffc000323ed4>] bus_for_each_dev+0x54/0xa0
> >>> [<ffffffc0003258bc>] driver_attach+0x1c/0x40
> >>> [<ffffffc00032548c>] bus_add_driver+0x14c/0x220
> >>> [<ffffffc00032683c>] driver_register+0x5c/0x120
> >>> [<ffffffc000327cdc>] __platform_driver_register+0x5c/0x80
> >>> [<ffffffc0006a0c40>] xgene_pcie_driver_init+0x14/0x20
> >>> [<ffffffc0000814c0>] do_one_initcall+0xe0/0x160
> >>> [<ffffffc00068c934>] kernel_init_freeable+0x134/0x1d8
> >>> [<ffffffc0004f07ac>] kernel_init+0xc/0xe0
> >>> ---[ end trace 3ee052d463aab7f3 ]---
> >>> ------------[ cut here ]------------
> >>> WARNING: CPU: 0 PID: 1 at
> >>> /home/tinamdar/work/open-source/linux/drivers/pci/probe.c:1380
> >>> pci_device_add+0x128/0x140()
> >>> -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> >>>
> >>> I have made a small fix above your patch. After the fix is applied,
> >>> dumps are gone and the enumeration finishes up smoothly for all the
> >>> ports.
> >>> Since the change is small, just pasting it here. Please review and
> >>> apply if it's clean.
> >>
> >> Honestly, I have no idea. I kept staring at the code for a better part of an hour
> >> trying to decipher what the intent of the code was, without too much progress. I
> >> still don't understand why the code in pci_alloc_child_bus() takes a shortcut when
> >> the bridge argument is NULL when in my opinion it should use parent->bridge instead
> >> and continue as normal.
> >>
> >>>
> >>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> >>> index a12cda5..aac8366 100644
> >>> --- a/drivers/pci/probe.c
> >>> +++ b/drivers/pci/probe.c
> >>> @@ -693,7 +693,7 @@ static struct pci_bus *pci_alloc_child_bus(struct
> >>> pci_bus *parent,
> >>> }
> >>>
> >>> child->self = bridge;
> >>> - child->bridge = get_device(&bridge->dev);
> >>> + child->bridge = get_device(parent->bridge);
> >>> child->dev.parent = child->bridge;
> >>
> >> Hmm, not sure why this is needed. What does get_device(&bridge->dev)
> >> return for you? The next line sets child->dev.parent to child->bridge,
> >> but with your change I'm not sure we end up using the correct parent.
> >>
> >> Can you try to revert your change and modify the implementation of pci_domain_nr() in arm64
> >> to look like this:
> >>
> >> static inline int pci_domain_nr(struct pci_bus *bus)
> >> {
> >> struct pci_host_bridge *bridge;
> >>
> >> while (bus->parent)
> >> bus = bus->parent;
> >>
> >> bridge = to_pci_host_bridge(bus->bridge);
> >> if (bridge)
> >> return bridge->domain_nr;
> >>
> >> return 0;
> >> }
> >>
> >
> > This did not work for me.
> >
> >
> >> Please let me know what results you get.
> >>
> > I am printing following values
> >
> > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> > index a12cda5..c89f86a 100644
> > --- a/drivers/pci/probe.c
> > +++ b/drivers/pci/probe.c
> > @@ -695,6 +695,8 @@ static struct pci_bus *pci_alloc_child_bus(struct
> > pci_bus *parent,
> > child->self = bridge;
> > child->bridge = get_device(&bridge->dev);
> > child->dev.parent = child->bridge;
> > + printk("%s:%d bus = %p , bridge_dev = %p, domain = %d\n",
> > + __func__, __LINE__, child, child->bridge,
> > pci_domain_nr(parent));
> > pci_set_bus_of_node(child);
> > pci_set_bus_speed(child);
> >
> > @@ -1095,6 +1097,8 @@ int pci_setup_device(struct pci_dev *dev)
> > dev_set_name(&dev->dev, "%04x:%02x:%02x.%d", pci_domain_nr(dev->bus),
> > dev->bus->number, PCI_SLOT(dev->devfn),
> > PCI_FUNC(dev->devfn));
> > + printk("%s:%d bus = %p , bridge_dev = %p, domain = %d\n",
> > + __func__, __LINE__, dev->bus, dev->bus->bridge,
> > pci_domain_nr(dev->bus));
> >
> > pci_read_config_dword(dev, PCI_CLASS_REVISION, &class);
> > dev->revision = class & 0xff;
> >
> > Following looks suspicious to me.
> >
> > bridge_dev = ffffffc7e03ffc00 for bus 0 in domain 1 while bridge_dev =
> > ffffffc7e03f7098 for bus 1 in domain 1.
> >
> > Log -->
> > -----------------------------------------------------------------------------------------------------------------------------
> > xgene-pcie 1f500000.pcie: (rc) x8 gen-3 link up
> > pci_bus 0001:00: scanning bus
> > pci_setup_device:1101 bus = ffffffc7e0060400 , bridge_dev =
> > ffffffc7e03ffc00, domain = 1
> > pci 0001:00:00.0: [e008:e004] type 01 class 0x060400
> > pci 0001:00:00.0: reg 0x10: [mem 0x4000000000-0x7fffffffff 64bit]
> > pci 0001:00:00.0: calling xgene_pcie_fixup_bridge+0x0/0x80
> > pci 0001:00:00.0: Hiding X-Gene pci host bridge resources 0001:00:00.0
> > pci 0001:00:00.0: supports D1 D2
> > pci_bus 0001:00: fixups for bus
> > pci 0001:00:00.0: scanning [bus 03-03] behind bridge, pass 0
> > pci 0001:00:00.0: bridge configuration invalid ([bus 03-03]), reconfiguring
> > pci 0001:00:00.0: scanning [bus 00-00] behind bridge, pass 1
> > pci_alloc_child_bus:699 bus = ffffffc7e0063000 , bridge_dev =
> > ffffffc7e03f7098, domain = 1
> > pci_bus 0001:01: scanning bus
> > pci_setup_device:1101 bus = ffffffc7e0063000 , bridge_dev =
> > ffffffc7e03f7098, domain = 0
> > pci 0000:01:00.0: [15b3:1003] type 00 class 0x020000
> > pci 0000:01:00.0: reg 0x10: [mem 0x00100000-0x001fffff 64bit]
> > pci 0000:01:00.0: reg 0x18: [mem 0x00800000-0x00ffffff 64bit pref]
> > pci 0000:01:00.0: reg 0x30: [mem 0x01000000-0x010fffff pref]
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 1 at
> > /home/tinamdar/work/open-source/linux/fs/sysfs/dir.c:52
> > sysfs_warn_dup+0x80/0xc0()
> > sysfs: cannot create duplicate filename '/bus/pci/devices/0000:01:00.0'
> > Modules linked in:
> > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.0-rc5+ #50
> > -----------------------------------------------------------------------------------------------------------------------------
> >
> >
> >> Best regards,
> >> Liviu
> >>
> >>
> >>> pci_set_bus_of_node(child);
> >>> pci_set_bus_speed(child);
> >>>
> >>> Thanks,
> >>> Tanmay
> >>>
> >>> On Mon, Mar 3, 2014 at 9:33 AM, Liviu Dudau <Liviu.Dudau at arm.com> wrote:
> >>> > pci_alloc_child_bus() uses the newly allocated child bus to figure
> >>> > out the domain number that is going to use for setting the device
> >>> > name. A better option is to use the parent bus domain number.
> >>> >
> >>> > Signed-off-by: Liviu Dudau <Liviu.Dudau at arm.com>
> >>> >
> >>> > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> >>> > index 26237a0..a12cda5 100644
> >>> > --- a/drivers/pci/probe.c
> >>> > +++ b/drivers/pci/probe.c
> >>> > @@ -677,7 +677,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
> >>> > * now as the parent is not properly set up yet.
> >>> > */
> >>> > child->dev.class = &pcibus_class;
> >>> > - dev_set_name(&child->dev, "%04x:%02x", pci_domain_nr(child), busnr);
> >>> > + dev_set_name(&child->dev, "%04x:%02x", pci_domain_nr(parent), busnr);
> >>> >
> >>> > /*
> >>> > * Set up the primary, secondary and subordinate
> >>> > --
> >>> > 1.9.0
> >>> >
> >>> --
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> >>>
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