linux-kernel - Re: Please revert 928bea964827d7824b548c1f8e06eccbbc4d0d7d

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Message-ID: <CAE9FiQW+b7OtN4hJc6uygzbqzaCOkn3WcLDgSg5isHAJfdgmwg@mail.gmail.com>
Date:	Fri, 27 Sep 2013 10:44:44 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
	Linux Kernel list <linux-kernel@...r.kernel.org>
Subject: Re: Please revert 928bea964827d7824b548c1f8e06eccbbc4d0d7d

On Fri, Sep 27, 2013 at 9:01 AM, Yinghai Lu <yinghai@...nel.org> wrote:
> On Fri, Sep 27, 2013 at 1:28 AM, Benjamin Herrenschmidt
> <benh@...nel.crashing.org> wrote:
>> Hi Linus, Yinghai !
>>
>> Please consider reverting:
>>
>> 928bea964827d7824b548c1f8e06eccbbc4d0d7d
>> PCI: Delay enabling bridges until they're needed
>>
>> (I'd suggest to revert now and maybe merge a better patch later)
>>
>> This breaks PCI on the PowerPC "powernv" platform (which is booted via
>> kexec) and probably x86 as well under similar circumstances. It will
>> basically break PCIe if the bus master bit of the bridge isn't set at
>> boot (by the firmware for example, or because kexec'ing cleared it).
>>
>> The reason is that the PCIe port driver will call pci_enable_device() on
>> the bridge (on everything under the sun actually), which will marked the
>> device enabled (but will not do a set_master).
>>
>> Because of that, pci_enable_bridge() later on (called as a result of the
>> child device driver doing pci_enable_device) will see the bridge as
>> already enabled and will not call pci_set_master() on it.

Ben,

looks like PCIe port driver does call pci_enable_device AND pci_set_master()

| int pcie_port_device_register(struct pci_dev *dev)
| {
|        int status, capabilities, i, nr_service;
|        int irqs[PCIE_PORT_DEVICE_MAXSERVICES];
|
|        /* Enable PCI Express port device */
|        status = pci_enable_device(dev);
|        if (status)
|                return status;
|
|        /* Get and check PCI Express port services */
|        capabilities = get_port_device_capability(dev);
|        if (!capabilities)
|                return 0;
|
|        pci_set_master(dev);

so how come that pci_set_master is not called for powerpc?

Can you send out lspci -vvxxx with current linus-tree and v3.11?

Yinghai
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