Messages in this thread Patch in this message | | | Date | Mon, 22 Dec 2014 12:46:12 -0500 | From | Murali Karicheri <> | Subject | Re: [RFC v1 PATCH 1/2] of/pci: add of_pci_dma_configure() update dma configuration |
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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. >> >> Signed-off-by: Murali Karicheri<m-karicheri2@ti.com> > > Much better! > > There is one detail that we should get right from the start here, > which is currently wrong in the platform device code, but I have so > far not dared change it: > >> + /* >> + * Set default dma-mask to 32 bit. Drivers are expected to setup >> + * the correct supported dma_mask. >> + */ >> + dev->coherent_dma_mask = DMA_BIT_MASK(32); > > The 32-bit mask is indeed correct as the default for almost all cases, > and we must not set it larger than DMA_BIT_MASK(32). There is one > corner case though, which happens on some shmobile machines that have > a 31-bit mask on the PCI host, and I think we should use that as the > default. > >> + /* >> + * 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;
> >> + } 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.
Murali
> Arnd
-- Murali Karicheri Linux Kernel, Texas Instruments
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