Re: [PATCH v4 01/21] pci: Add pcibios_setup_bridge()

[Gavin Shan <gwshan@linux.vnet.ibm.com>]

On Thu, May 07, 2015 at 05:12:24PM -0500, Bjorn Helgaas wrote:
>Hi Gavin,
>
>[Please run "git log --oneline drivers/pci/setup-bus.c" and observe the
>capitalization convention.]
>

Bjorn, thanks for review. Yeah, it should be something like
"PCI: xxxx" for the subject. I'll fix it up in next revision.

>On Fri, May 01, 2015 at 04:02:48PM +1000, Gavin Shan wrote:
>> Currently, PowerPC PowerNV platform utilizes ppc_md.pcibios_fixup(),
>> which is called for once after PCI probing and resource assignment
>> are completed, to allocate platform required resources for PCI devices:
>> PE#, IO and MMIO mapping, DMA address translation (TCE) table etc.
>> Obviously, it's not hotplug friendly.
>> 
>> The patch adds weak function pcibios_setup_bridge(), which is called
>> by pci_setup_bridge(). PowerPC PowerNV platform will reuse the function
>> to assign above platform required resources to newly added PCI devices,
>> in order to support PCI hotplug on PowerPC PowerNV platform.
>> 
>> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
>> ---
>>  drivers/pci/setup-bus.c | 12 +++++++++---
>>  include/linux/pci.h     |  1 +
>>  2 files changed, 10 insertions(+), 3 deletions(-)
>> 
>> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
>> index 4fd0cac..a7d0c3c 100644
>> --- a/drivers/pci/setup-bus.c
>> +++ b/drivers/pci/setup-bus.c
>> @@ -674,7 +674,8 @@ static void pci_setup_bridge_mmio_pref(struct pci_dev *bridge)
>>  	pci_write_config_dword(bridge, PCI_PREF_LIMIT_UPPER32, lu);
>>  }
>>  
>> -static void __pci_setup_bridge(struct pci_bus *bus, unsigned long type)
>> +
>> +void pci_setup_bridge_resources(struct pci_bus *bus, unsigned long type)
>>  {
>>  	struct pci_dev *bridge = bus->self;
>>  
>> @@ -693,12 +694,17 @@ static void __pci_setup_bridge(struct pci_bus *bus, unsigned long type)
>>  	pci_write_config_word(bridge, PCI_BRIDGE_CONTROL, bus->bridge_ctl);
>>  }
>>  
>> +void __weak pcibios_setup_bridge(struct pci_bus *bus, unsigned long type)
>> +{
>> +	pci_setup_bridge_resources(bus, type);
>> +}
>
>I'm not opposed to adding a pcibios_setup_bridge(), but I would rather do
>the architected updates in the generic PCI core code instead of down in the
>pcibios code.  In other words, I would rather have this:
>
>  void pci_setup_bridge(struct pci_bus *bus)
>  {
>    pcibios_setup_bridge(bus, type);
>    pci_setup_bridge_resources(bus, type);
>  }
>
>That way the default pcibios hook is empty, showing that by default there's
>no arch-specific code in this path, and we only have to look at the generic
>core code to verify that we actually do program the bridge windows.
>

Ok. I'll change the code accordingly in next revision. Thanks for the
suggestion.

Thanks,
Gavin