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Commit 9f28cde0 authored by Russell King's avatar Russell King
Browse files

ARM: another fix for the DMA mapping checks 



Peter reports that OMAP audio broke with the recent fix for these
checks, caused by OMAP audio using a 64-bit DMA mask.  We should
allow 64-bit DMA masks even with 32-bit dma_addr_t if we can be sure
the amount of RAM we have won't allow the 32-bit dma_addr_t to
overflow.  Unfortunately, the checks to detect overflow were not
correct.

Tested-by: default avatarPeter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 11d4bb1b

arch/arm/mm/dma-mapping.c

+40 −51
Original line number Diff line number Diff line
@@ -158,52 +158,62 @@ struct dma_map_ops arm_coherent_dma_ops = { 
};

EXPORT_SYMBOL(arm_coherent_dma_ops);



static u64 get_coherent_dma_mask(struct device *dev)

static int __dma_supported(struct device *dev, u64 mask, bool warn)

{

	u64 mask = (u64)DMA_BIT_MASK(32);



	if (dev) {

	unsigned long max_dma_pfn;



		mask = dev->coherent_dma_mask;



		/*

		 * Sanity check the DMA mask - it must be non-zero, and

		 * must be able to be satisfied by a DMA allocation.

		 */

		if (mask == 0) {

			dev_warn(dev, "coherent DMA mask is unset\n");

			return 0;

		}



		max_dma_pfn = min(max_pfn, arm_dma_pfn_limit);



	/*

	 * If the mask allows for more memory than we can address,

		 * and we actually have that much memory, then fail the

		 * allocation.

	 * and we actually have that much memory, then we must

	 * indicate that DMA to this device is not supported.

	 */

	if (sizeof(mask) != sizeof(dma_addr_t) &&

	    mask > (dma_addr_t)~0 &&

		    dma_to_pfn(dev, ~0) > max_dma_pfn) {

	    dma_to_pfn(dev, ~0) < max_pfn) {

		if (warn) {

			dev_warn(dev, "Coherent DMA mask %#llx is larger than dma_addr_t allows\n",

				 mask);

			dev_warn(dev, "Driver did not use or check the return value from dma_set_coherent_mask()?\n");

		}

		return 0;

	}



	max_dma_pfn = min(max_pfn, arm_dma_pfn_limit);



	/*

		 * Now check that the mask, when translated to a PFN,

		 * fits within the allowable addresses which we can

		 * allocate.

	 * Translate the device's DMA mask to a PFN limit.  This

	 * PFN number includes the page which we can DMA to.

	 */

	if (dma_to_pfn(dev, mask) < max_dma_pfn) {

		if (warn)

			dev_warn(dev, "Coherent DMA mask %#llx (pfn %#lx-%#lx) covers a smaller range of system memory than the DMA zone pfn 0x0-%#lx\n",

				 mask,

				 dma_to_pfn(dev, 0), dma_to_pfn(dev, mask) + 1,

				 arm_dma_pfn_limit + 1);

				 max_dma_pfn + 1);

		return 0;

	}



	return 1;

}



static u64 get_coherent_dma_mask(struct device *dev)

{

	u64 mask = (u64)DMA_BIT_MASK(32);



	if (dev) {

		mask = dev->coherent_dma_mask;



		/*

		 * Sanity check the DMA mask - it must be non-zero, and

		 * must be able to be satisfied by a DMA allocation.

		 */

		if (mask == 0) {

			dev_warn(dev, "coherent DMA mask is unset\n");

			return 0;

		}



		if (!__dma_supported(dev, mask, true))

			return 0;

	}



	return mask;
@@ -1032,28 +1042,7 @@ void arm_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, 
 */

int dma_supported(struct device *dev, u64 mask)

{

	unsigned long limit;



	/*

	 * If the mask allows for more memory than we can address,

	 * and we actually have that much memory, then we must

	 * indicate that DMA to this device is not supported.

	 */

	if (sizeof(mask) != sizeof(dma_addr_t) &&

	    mask > (dma_addr_t)~0 &&

	    dma_to_pfn(dev, ~0) > arm_dma_pfn_limit)

		return 0;



	/*

	 * Translate the device's DMA mask to a PFN limit.  This

	 * PFN number includes the page which we can DMA to.

	 */

	limit = dma_to_pfn(dev, mask);



	if (limit < arm_dma_pfn_limit)

		return 0;



	return 1;

	return __dma_supported(dev, mask, false);

}

EXPORT_SYMBOL(dma_supported);