On Monday 22 December 2014 12:46:12 Murali Karicheri wrote:
> On 12/18/2014 05:29 PM, Arnd Bergmann wrote:
> > On Thursday 18 December 2014 17:07:04 Murali Karicheri wrote:
> >> Add of_pci_dma_configure() to allow updating the dma configuration
> >> of the pci device using the configuration from the parent of
> >> the root bridge device.
> >> + /*
> >> + * Set it to coherent_dma_mask by default if the architecture
> >> + * code has not set it.
> >> + */
> >> + if (!dev->dma_mask)
> >> + dev->dma_mask =&dev->coherent_dma_mask;
> >> +
> >> + ret = of_dma_get_range(parent_np,&dma_addr,&paddr,&size);
> >> + if (ret< 0) {
> >> + dma_addr = offset = 0;
> >> + size = dev->coherent_dma_mask;
> >
> > Can you check one thing here? I believe the size argument as returned
> > from of_dma_get_range is inclusive (e.g. 0x100000000), while the coherent
> > mask by definition is exlusive (e.g. 0xffffffff), so the size needs to
> > be adapted here. I haven't checked all the code here though, so I may
> > be wrong.
>
> size returned by of_dma_get_range() is inclusive as you indicated. Fromt
> the grep of dma-ranges in arch/arm/boot/dts, I see
>
> arch/arm/boot/dts/keystone.dtsi: dma-ranges = <0x80000000 0x8
> 0x00000000 0x80000000>;
> arch/arm/boot/dts/keystone.dtsi: dma-ranges;
> arch/arm/boot/dts/r8a7790.dtsi: dma-ranges = <0x42000000 0 0x40000000 0
> 0x40000000 0 0x80000000
> arch/arm/boot/dts/integratorap.dts: dma-ranges = <0x80000000 0x0
> 0x80000000>;
> arch/arm/boot/dts/r8a7791.dtsi: dma-ranges = <0x42000000 0 0x40000000 0
> 0x40000000 0 0x80000000
>
> So I guess I need to change the code to
>
> >> + ret = of_dma_get_range(parent_np,&dma_addr,&paddr,&size);
> >> + if (ret< 0) {
> >> + dma_addr = offset = 0;
> >> + size = dev->coherent_dma_mask + 1;
Right.
> >> + } else {
> >> + offset = PFN_DOWN(paddr - dma_addr);
> >> + dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", dev->dma_pfn_offset);
> >> + }
> >> + dev->dma_pfn_offset = offset;
> >> +
> >> + coherent = of_dma_is_coherent(parent_np);
> >> + dev_dbg(dev, "device is%sdma coherent\n",
> >> + coherent ? " " : " not ");
> >> +
> >> + arch_setup_dma_ops(dev, dma_addr, size, NULL, coherent);
> >
> > Basically, I would use limit the size argument we pass into
> > arch_setup_dma_ops to the minimum of 'size' and 'dma_mask' here,
> > after converting into the same format. We should make sure we do the
> > same thing for platform_device as well, so it might be better to do
> > it inside of arch_setup_dma_ops instead.
>
> Do you think following changes will work?
>
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -2052,9 +2052,10 @@ void arch_setup_dma_ops(struct device *dev, u64
> dma_base, u64 size,
> struct iommu_ops *iommu, bool coherent)
> {
> struct dma_map_ops *dma_ops;
> + u64 temp_size = min((*(dev->dma_mask) + 1), size);
>
> dev->archdata.dma_coherent = coherent;
> - if (arm_setup_iommu_dma_ops(dev, dma_base, size, iommu))
> + if (arm_setup_iommu_dma_ops(dev, dma_base, temp_size, iommu))
>
> If you agree, I will post v1 of the patch with these updates. Let me
> know. I did some basic tests on Keystone with these changes and it works
> fine.
It's not exactly what I meant. My main point was that we need to limit
dev->dma_mask to (size-1) here, but you are not touching that. We can
either change the two functions in which we first assign the dma_mask
(platform and pci bus), or set it again in arch_setup_dma_ops (on each
architecture implementing it), either way would work. Someone else
might have a stronger opinion on that matter.
For arm_setup_iommu_dma_ops, passing the original size is probably
best.
Arnd
--
To unsubscribe from this list: send the line "unsubscribe linux-pci" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
