Messages in this thread | | | Subject | Re: [PATCH V2 1/2] ACPI / scan: Support multiple dma windows with different offsets | From | Jianmin Lv <> | Date | Mon, 29 Aug 2022 21:00:30 +0800 |
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On 2022/8/12 下午3:52, Lorenzo Pieralisi wrote: > On Fri, Aug 05, 2022 at 01:46:07PM +0100, Robin Murphy wrote: > > [...] > >>> -int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset, >>> - u64 *size) >>> +int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map) >>> { >>> struct acpi_device *adev; >>> LIST_HEAD(list); >>> struct resource_entry *rentry; >>> int ret; >>> struct device *dma_dev = dev; >>> - u64 len, dma_start = U64_MAX, dma_end = 0, dma_offset = 0; >>> + int num_ranges = 0; >>> + struct bus_dma_region *r; >>> /* >>> * Walk the device tree chasing an ACPI companion with a _DMA >>> @@ -1525,31 +1526,31 @@ int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset, >>> ret = acpi_dev_get_dma_resources(adev, &list); >>> if (ret > 0) { >>> + list_for_each_entry(rentry, &list, node) >>> + num_ranges++; >> >> We already have the number of resources in ret. >> >> Looking at this, I also now wonder if we're doing the right thing if the >> object is present but contains no resources. The spec isn't clear whether >> that's even really valid, but if it is, is it meaningful? It seems we'd >> currently consider an empty object equivalent to no object, but if anything >> it should perhaps be interpreted as the opposite, i.e. that no DMA is >> possible because the bus does not decode any ranges. Is anyone more familiar >> with the intent of the spec here? > > I think we are currently considering no object differently from an > empty object, since for no object we would return -ENODEV in > acpi_dma_get_range(), we would not even get to parsing the resources > (and return 0) and we would fall back to checking IORT to gather the > DMA address space size. > > I think you are right, we should change the behaviour if an object > is present but it has no resources though, by reading the specs an > empty _DMA object implies no DMA is possible and that's not what > we are doing at the moment (hopefully there is no firmware out > there with such a set-up but there is only one way to discover it). > > This behavioural change should be a separate patch obviously for > bisectability (and a possible revert). > > Lorenzo > Hi, Robin and Lorenzo
For the issue of empty _DMA, I consulted ASWG(ACPI Spec Work Group), and received an reply from some people that an _DMA object is allowed to contain *no* resources, and indicates disabled DMA(some arm systems are being used empty _DMA as an indicator to the OS that DMA is disabled for specified device). ASWG has isssued an request to clarify it in spec after approved.
I think we can submit a seperate patch for that after it is confirmed.
Thanks.
>> Thanks, >> Robin. >> >>> + >>> + r = kcalloc(num_ranges + 1, sizeof(*r), GFP_KERNEL); >>> + if (!r) { >>> + ret = -ENOMEM; >>> + goto out; >>> + } >>> + >>> + *map = r; >>> + >>> list_for_each_entry(rentry, &list, node) { >>> - if (dma_offset && rentry->offset != dma_offset) { >>> + if (rentry->res->start >= rentry->res->end) { >>> ret = -EINVAL; >>> - dev_warn(dma_dev, "Can't handle multiple windows with different offsets\n"); >>> + dev_dbg(dma_dev, "Invalid DMA regions configuration\n"); >>> goto out; >>> } >>> - dma_offset = rentry->offset; >>> - >>> - /* Take lower and upper limits */ >>> - if (rentry->res->start < dma_start) >>> - dma_start = rentry->res->start; >>> - if (rentry->res->end > dma_end) >>> - dma_end = rentry->res->end; >>> - } >>> - if (dma_start >= dma_end) { >>> - ret = -EINVAL; >>> - dev_dbg(dma_dev, "Invalid DMA regions configuration\n"); >>> - goto out; >>> + r->cpu_start = rentry->res->start; >>> + r->dma_start = rentry->res->start - rentry->offset; >>> + r->size = rentry->res->end - rentry->res->start + 1; >>> + r->offset = rentry->offset; >>> + r++; >>> } >>> - *dma_addr = dma_start - dma_offset; >>> - len = dma_end - dma_start; >>> - *size = max(len, len + 1); >>> - *offset = dma_offset; >>> } >>> out: >>> acpi_dev_free_resource_list(&list); >>> @@ -1639,20 +1640,19 @@ int acpi_dma_configure_id(struct device *dev, enum dev_dma_attr attr, >>> const u32 *input_id) >>> { >>> const struct iommu_ops *iommu; >>> - u64 dma_addr = 0, size = 0; >>> if (attr == DEV_DMA_NOT_SUPPORTED) { >>> set_dma_ops(dev, &dma_dummy_ops); >>> return 0; >>> } >>> - acpi_arch_dma_setup(dev, &dma_addr, &size); >>> + acpi_arch_dma_setup(dev); >>> iommu = acpi_iommu_configure_id(dev, input_id); >>> if (PTR_ERR(iommu) == -EPROBE_DEFER) >>> return -EPROBE_DEFER; >>> - arch_setup_dma_ops(dev, dma_addr, size, >>> + arch_setup_dma_ops(dev, 0, U64_MAX, >>> iommu, attr == DEV_DMA_COHERENT); >>> return 0; >>> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h >>> index 0dc1ea0b..e106073 100644 >>> --- a/include/acpi/acpi_bus.h >>> +++ b/include/acpi/acpi_bus.h >>> @@ -611,8 +611,7 @@ struct acpi_pci_root { >>> int acpi_iommu_fwspec_init(struct device *dev, u32 id, >>> struct fwnode_handle *fwnode, >>> const struct iommu_ops *ops); >>> -int acpi_dma_get_range(struct device *dev, u64 *dma_addr, u64 *offset, >>> - u64 *size); >>> +int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map); >>> int acpi_dma_configure_id(struct device *dev, enum dev_dma_attr attr, >>> const u32 *input_id); >>> static inline int acpi_dma_configure(struct device *dev, >>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h >>> index 44975c1..34e0545 100644 >>> --- a/include/linux/acpi.h >>> +++ b/include/linux/acpi.h >>> @@ -280,12 +280,12 @@ int acpi_table_parse_madt(enum acpi_madt_type id, >>> #ifdef CONFIG_ARM64 >>> void acpi_numa_gicc_affinity_init(struct acpi_srat_gicc_affinity *pa); >>> -void acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size); >>> +void acpi_arch_dma_setup(struct device *dev); >>> #else >>> static inline void >>> acpi_numa_gicc_affinity_init(struct acpi_srat_gicc_affinity *pa) { } >>> static inline void >>> -acpi_arch_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size) { } >>> +acpi_arch_dma_setup(struct device *dev) { } >>> #endif >>> int acpi_numa_memory_affinity_init (struct acpi_srat_mem_affinity *ma); >>> @@ -974,8 +974,7 @@ static inline enum dev_dma_attr acpi_get_dma_attr(struct acpi_device *adev) >>> return DEV_DMA_NOT_SUPPORTED; >>> } >>> -static inline int acpi_dma_get_range(struct device *dev, u64 *dma_addr, >>> - u64 *offset, u64 *size) >>> +static inline int acpi_dma_get_range(struct device *dev, const struct bus_dma_region **map) >>> { >>> return -ENODEV; >>> }
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