linux-kernel - Re: [PATCH 5/8] PCI: add generic device into pci_host

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Message-ID: <CAE9FiQUDtJc5uwPXkQ7T7zr8=xa=VnPuQT4Q87SXbynuCHQ2Zg@mail.gmail.com>
Date:	Mon, 27 Feb 2012 11:08:51 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	Jesse Barnes <jbarnes@...tuousgeek.org>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/8] PCI: add generic device into pci_host_bridge struct

On Mon, Feb 27, 2012 at 9:57 AM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
> On Sun, Feb 26, 2012 at 4:33 PM, Yinghai Lu <yinghai@...nel.org> wrote:
>> use that device for pci_root_bus bridge pointer.
>>
>> With that make code more simple.
>>
>> Also we can use pci_release_bus_bridge_dev() to release allocated
>> pci_host_bridge during removing path.
>>
>> At last, we can use root bus bridge pointer to get host bridge pointer instead
>> of going over host bridge list, so could kill that host bridge list.
>>
>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>>
>> ---
>>  drivers/pci/host-bridge.c |   14 ---------
>>  drivers/pci/pci.h         |    2 -
>>  drivers/pci/probe.c       |   65 ++++++++++++++++++++++++----------------------
>>  include/linux/pci.h       |    4 ++
>>  4 files changed, 38 insertions(+), 47 deletions(-)
>>
>> Index: linux-2.6/drivers/pci/host-bridge.c
>> ===================================================================
>> --- linux-2.6.orig/drivers/pci/host-bridge.c
>> +++ linux-2.6/drivers/pci/host-bridge.c
>> -       dev = kzalloc(sizeof(*dev), GFP_KERNEL);
>> -       if (!dev)
>> -               goto err_dev;
>> +               return NULL;
>>
...

here old code allocate dummy struct device.

>> +       bridge = pci_alloc_host_bridge(b);
>> +       if (!bridge)
>> +               goto err_out;
>> +
>> +       bridge->dev.parent = parent;
>> +       bridge->dev.release = pci_release_bus_bridge_dev;
>> +       dev_set_name(&bridge->dev, "pci%04x:%02x", pci_domain_nr(b), bus);
>> +       error = device_register(&bridge->dev);
>>        if (error)
>> -               goto dev_reg_err;
>> -       b->bridge = get_device(dev);
>> +               goto bridge_dev_reg_err;
>> +       b->bridge = get_device(&bridge->dev);
...
>> --- linux-2.6.orig/include/linux/pci.h
>> +++ linux-2.6/include/linux/pci.h
>> @@ -375,11 +375,13 @@ struct pci_host_bridge_window {
>>  };
>>
>>  struct pci_host_bridge {
>> -       struct list_head list;
>> +       struct device dev;
>>        struct pci_bus *bus;            /* root bus */
>>        struct list_head windows;       /* pci_host_bridge_windows */
>>  };
>
> This doesn't feel right to me.  You're allocating a new struct device
> here, but the arch likely already has one.  In fact, I think we even
> passed it in to pci_create_root_bus().

no.

original pci_create_root_bus() will create one dummy struct device and
use it as parent for bus->dev.

>
> On x86, we already have an ACPI device for the host bridge, and now
> we'll have a second one.  (Actually a *third* one, because PNPACPI
> also has one, but that's a long-standing problem.)

not related.

      Yinghai
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