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

[Kumar Gala <galak@kernel.crashing.org>]

On Nov 27, 2012, at 8:34 PM, Chen Yuanquan-B41889 wrote:

> On 11/25/2012 08:41 PM, Kumar Gala wrote:
>> On Nov 22, 2012, at 10:29 PM, Yuanquan Chen wrote:
>>=20
>>> 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.
>>>=20
>>> Signed-off-by: Yuanquan Chen <B41889@freescale.com>
>>> ---
>>> 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.
>>=20
>> - k
>=20
> Hi Kumar,
>=20
> 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?
>=20
> Thanks,
> yuanquan
>=20
> 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;
>=20
> +       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);
> }
>=20

This looks better than the first patch..  I'm surprised that the IBM =
guys don't run into a similar issue with their hotplug support.

Maybe Ben or someone else will comment.

- k

>>> 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 =3D get_dma_ops(dev);
>>>=20
>>> -	if (unlikely(dma_ops =3D=3D NULL))
>>> -		return 0;
>>> +	if (unlikely(dma_ops =3D=3D NULL)) {
>>> +		set_dma_ops(dev, &dma_direct_ops);
>>> +		set_dma_offset(dev, PCI_DRAM_OFFSET);
>>> +		dma_ops =3D &dma_direct_ops;
>>> +	}
>>> 	if (dma_ops->dma_supported =3D=3D NULL)
>>> 		return 1;
>>> 	return dma_ops->dma_supported(dev, mask);
>>> --=20
>>> 1.7.9.5
>>>=20
>>>=20
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>>> Linuxppc-dev@lists.ozlabs.org
>>> https://lists.ozlabs.org/listinfo/linuxppc-dev
>>=20
>>=20
>>=20
>=20