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List:       linuxppc-embedded
Subject:    Re: [PATCH] powerpc/pci-hotplug: fix the rescanned pci device's dma_set_mask issue
From:       Kumar Gala <galak () kernel ! crashing ! org>
Date:       2012-11-28 17:34:17
Message-ID: 42C14AFA-42D6-498D-9B38-A02CEAC2D0BA () kernel ! crashing ! org
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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:
> > 
> > > 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 <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. 
> > - 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);
> }
> 

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 = 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
> > > Linuxppc-dev@lists.ozlabs.org
> > > https://lists.ozlabs.org/listinfo/linuxppc-dev
> > 
> > 
> > 
> 

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