Commit ba503cf4 authored by Robin Murphy's avatar Robin Murphy Committed by Joerg Roedel
Browse files

OF: Simplify DMA range calculations 



Juggling start, end, and size values for a range is somewhat redundant
and a little hard to follow. Consolidate down to just using inclusive
start and end, which saves us worrying about size overflows for full
64-bit ranges (note that passing a potentially-overflowed value through
to arch_setup_dma_ops() is benign for all current implementations, and
this is working towards removing that anyway).

Acked-by: default avatarRob Herring <robh@kernel.org>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/3e0a72fe3d79eae660e4284bb32f2cb39868ccd7.1713523152.git.robin.murphy@arm.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 0c345792

drivers/of/device.c

+8 −11
Original line number Diff line number Diff line
@@ -96,7 +96,7 @@ int of_dma_configure_id(struct device *dev, struct device_node *np, 
	const struct bus_dma_region *map = NULL;

	struct device_node *bus_np;

	u64 dma_start = 0;

	u64 mask, end, size = 0;

	u64 mask, end = 0;

	bool coherent;

	int iommu_ret;

	int ret;
@@ -118,17 +118,15 @@ int of_dma_configure_id(struct device *dev, struct device_node *np, 
			return ret == -ENODEV ? 0 : ret;

	} else {

		const struct bus_dma_region *r = map;

		u64 dma_end = 0;



		/* Determine the overall bounds of all DMA regions */

		for (dma_start = ~0; r->size; r++) {

			/* Take lower and upper limits */

			if (r->dma_start < dma_start)

				dma_start = r->dma_start;

			if (r->dma_start + r->size > dma_end)

				dma_end = r->dma_start + r->size;

			if (r->dma_start + r->size > end)

				end = r->dma_start + r->size;

		}

		size = dma_end - dma_start;

	}



	/*
@@ -142,16 +140,15 @@ int of_dma_configure_id(struct device *dev, struct device_node *np, 
		dev->dma_mask = &dev->coherent_dma_mask;

	}



	if (!size && dev->coherent_dma_mask)

		size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);

	else if (!size)

		size = 1ULL << 32;

	if (!end && dev->coherent_dma_mask)

		end = dev->coherent_dma_mask;

	else if (!end)

		end = (1ULL << 32) - 1;



	/*

	 * Limit coherent and dma mask based on size and default mask

	 * set by the driver.

	 */

	end = dma_start + size - 1;

	mask = DMA_BIT_MASK(ilog2(end) + 1);

	dev->coherent_dma_mask &= mask;

	*dev->dma_mask &= mask;
@@ -185,7 +182,7 @@ int of_dma_configure_id(struct device *dev, struct device_node *np, 
	} else

		dev_dbg(dev, "device is behind an iommu\n");



	arch_setup_dma_ops(dev, dma_start, size, coherent);

	arch_setup_dma_ops(dev, dma_start, end - dma_start + 1, coherent);



	if (iommu_ret)

		of_dma_set_restricted_buffer(dev, np);