Messages in this thread Patches in this message | | | From | Roger Quadros <> | Subject | dma_mask limited to 32-bits with OF platform device | Date | Wed, 12 Feb 2020 12:49:59 +0200 |
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Hi,
I'd like to understand why of_dma_configure() is limiting the dma and coherent masks instead of overriding them.
see commits a5516219b102 ("of/platform: Initialise default DMA masks") ee7b1f31200d ("of: fix DMA mask generation")
In of_platform_device_create_pdata(), we initialize both masks to 32-bits unconditionally, which is fine to support legacy cases.
dev->dev.coherent_dma_mask = DMA_BIT_MASK(32); if (!dev->dev.dma_mask) dev->dev.dma_mask = &dev->dev.coherent_dma_mask;
Then in of_dma_configure() we limit it like so.
dev->coherent_dma_mask &= mask; *dev->dma_mask &= mask;
This way, legitimate devices which correctly set dma-ranges in DT will never get a dma_mask above 32-bits at all. How is this expected to work?
For a test, I added this in dra7.dtsi sata node. (NOTE: CONFIG_ARM_LPAE=y)
diff --git a/arch/arm/boot/dts/dra7.dtsi b/arch/arm/boot/dts/dra7.dtsi index 93aa65c75b45..cd8c6cea23d5 100644 --- a/arch/arm/boot/dts/dra7.dtsi +++ b/arch/arm/boot/dts/dra7.dtsi @@ -571,6 +571,8 @@ sata: sata@4a141100 { compatible = "snps,dwc-ahci"; reg = <0x4a140000 0x1100>, <0x4a141100 0x7>; + #size-cells = <2>; + dma-ranges = <0x00000000 0x00000000 0x10 0x00000000>; interrupts = <GIC_SPI 49 IRQ_TYPE_LEVEL_HIGH>; phys = <&sata_phy>; phy-names = "sata-phy"; ----------------------------- drivers/of/device.c ----------------------------- index e9127db7b067..1072cebad57a 100644 @@ -95,6 +95,7 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma) const struct iommu_ops *iommu; u64 mask, end; + dev_info(dev, "of_dma_configure\n"); ret = of_dma_get_range(np, &dma_addr, &paddr, &size); if (ret < 0) { /* @@ -123,7 +124,8 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma) dev_err(dev, "Adjusted size 0x%llx invalid\n", size); return -EINVAL; } - dev_dbg(dev, "dma_pfn_offset(%#08lx)\n", offset); + dev_info(dev, "dma %llx paddr %llx size %llx\n", dma_addr, paddr, size); + dev_info(dev, "dma_pfn_offset(%#08lx)\n", offset); } /* @@ -152,6 +154,8 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma) mask = DMA_BIT_MASK(ilog2(end) + 1); dev->coherent_dma_mask &= mask; *dev->dma_mask &= mask; + + dev_info(dev, "end %llx, mask %llx\n", end, mask); /* ...but only set bus limit if we found valid dma-ranges earlier */ if (!ret) dev->bus_dma_limit = end; And I see.
[ 1.134294] 4a140000.sata: of_platform [ 13.203917] ahci 4a140000.sata: of_dma_configure [ 13.225635] ahci 4a140000.sata: dma 0 paddr 0 size 1000000000 [ 13.266178] ahci 4a140000.sata: dma_pfn_offset(0x000000) [ 13.297621] ahci 4a140000.sata: end fffffffff, mask fffffffff [ 13.585499] ahci 4a140000.sata: dma_mask 0xffffffff, coherent_mask 0xffffffff [ 13.599082] ahci 4a140000.sata: setting 64-bit mask ffffffffffffffff Truncation of dma_mask and coherent_mask is undesired in this case.
How about fixing it like so?
- dev->coherent_dma_mask &= mask; - *dev->dma_mask &= mask; + dev->coherent_dma_mask = mask; + *dev->dma_mask = mask;
Also this comment doesn't make sense anymore?
/* * Limit coherent and dma mask based on size and default mask * set by the driver. */ cheers, -roger -- Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
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