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@xxxxxx>
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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