Subject: Re: [PATCH] powerpc/pci-hotplug: fix the rescanned pci device's dma_set_mask issue

From: Chen Yuanquan-B41889 <[email-masked]>
Date: Wed, 28 Nov 2012 10:34:18 +0800

On 11/25/2012 08:41 PM, Kumar Gala wrote:
> On Nov 22, 2012, at 10:29 PM, Yuanquan Chen wrote:
>
>> On powerpc arch, dma_ops of rescanned pci device after system's booting up won't be
>> initialized by system, so it will fail to execute the dma_set_mask in the device's
>> driver. Initialize it to solve this issue.
>>
>> Signed-off-by: Yuanquan Chen <[email-masked]>
>> ---
>> arch/powerpc/include/asm/dma-mapping.h |    7 +++++--
>> 1 file changed, 5 insertions(+), 2 deletions(-)
> This is not the right way to get the dma_ops setup.  You need to find some other point for the hotplug scenario to get the dma_ops setup.
>
> - k

Hi Kumar,

I read the code about pci bus scan and rescan. Only the 
pcibios_fixup_bus in pci_scan_child_bus and
pcibios_enable_device in pci_rescan_bus are arch related code. The 
pcibios_fixup_bus won't be called
for the rescanned PCI devices due to the bus->is_added has been set for 
the first scanning at boot time.
So I think it's more reasonable to do the same work as pcibios_fixup_bus 
for rescanned PCI device in
pcibios_enable_device. The patch code is a copy of 
pcibios_setup_bus_devices called by pcibios_fixup_bus,
It can solve the dma_set_mask and irq related issues of rescanned PCI 
device on powerpc arch. What's
your opinion?

Thanks,
yuanquan

diff --git a/arch/powerpc/kernel/pci-common.c 
b/arch/powerpc/kernel/pci-common.c
index 7f94f76..30f7d61 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -1496,6 +1496,23 @@ int pcibios_enable_device(struct pci_dev *dev, 
int mask)
                 if (ppc_md.pcibios_enable_device_hook(dev))
                         return -EINVAL;

+       if (!dev->is_added) {
+               set_dev_node(&dev->dev, pcibus_to_node(dev->bus));
+
+               /* Hook up default DMA ops */
+               set_dma_ops(&dev->dev, pci_dma_ops);
+               set_dma_offset(&dev->dev, PCI_DRAM_OFFSET);
+
+               /* Additional platform DMA/iommu setup */
+               if (ppc_md.pci_dma_dev_setup)
+                       ppc_md.pci_dma_dev_setup(dev);
+
+               /* Read default IRQs and fixup if necessary */
+               pci_read_irq_line(dev);
+               if (ppc_md.pci_irq_fixup)
+                       ppc_md.pci_irq_fixup(dev);
+       }
+
         return pci_enable_resources(dev, mask);
  }

>> diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h
>> index 7816087..22eae53 100644
>> --- a/arch/powerpc/include/asm/dma-mapping.h
>> +++ b/arch/powerpc/include/asm/dma-mapping.h
>> @@ -126,8 +126,11 @@ static inline int dma_supported(struct device *dev, u64 mask)
>> {
>> 	struct dma_map_ops *dma_ops = get_dma_ops(dev);
>>
>> -	if (unlikely(dma_ops == NULL))
>> -		return 0;
>> +	if (unlikely(dma_ops == NULL)) {
>> +		set_dma_ops(dev, &dma_direct_ops);
>> +		set_dma_offset(dev, PCI_DRAM_OFFSET);
>> +		dma_ops = &dma_direct_ops;
>> +	}
>> 	if (dma_ops->dma_supported == NULL)
>> 		return 1;
>> 	return dma_ops->dma_supported(dev, mask);
>> -- 
>> 1.7.9.5
>>
>>
>> _______________________________________________
>> Linuxppc-dev mailing list
>> [email-masked]
>> https://lists.ozlabs.org/listinfo/linuxppc-dev
>
>
>