Unverified Commit 12b82775 authored by Heiko Stuebner's avatar Heiko Stuebner Committed by Palmer Dabbelt
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of: also handle dma-noncoherent in of_dma_is_coherent() 



of_dma_is_coherent() currently expects the architecture to be
non-coherent and some devices being coherent getting marked
as such with the dma-coherent devicetree property.

For PowerPC CONFIG_OF_DMA_DEFAULT_COHERENT was added which currently
makes of_dma_is_coherent() always return true but doesn't handle
the case of the architecture being coherent but some devices not.

So modify the function to also check for dma-noncoherent and
set a suitable default return value. If CONFIG_OF_DMA_DEFAULT_COHERENT
is set the value starts with true and finding dma-noncoherent will
set it to false and without CONFIG_OF_DMA_DEFAULT_COHERENT, the
behaviour is reversed.

Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarRob Herring <robh@kernel.org>
Reviewed-by: default avatarGuo Ren <guoren@kernel.org>
Signed-off-by: default avatarHeiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20220706231536.2041855-2-heiko@sntech.de


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 73448ae6

drivers/of/address.c

+10 −7
Original line number Diff line number Diff line
@@ -1045,26 +1045,29 @@ phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np) 
 *

 * It returns true if "dma-coherent" property was found

 * for this device in the DT, or if DMA is coherent by

 * default for OF devices on the current platform.

 * default for OF devices on the current platform and no

 * "dma-noncoherent" property was found for this device.

 */

bool of_dma_is_coherent(struct device_node *np)

{

	struct device_node *node;



	if (IS_ENABLED(CONFIG_OF_DMA_DEFAULT_COHERENT))

		return true;

	bool is_coherent = IS_ENABLED(CONFIG_OF_DMA_DEFAULT_COHERENT);



	node = of_node_get(np);



	while (node) {

		if (of_property_read_bool(node, "dma-coherent")) {

			of_node_put(node);

			return true;

			is_coherent = true;

			break;

		}

		if (of_property_read_bool(node, "dma-noncoherent")) {

			is_coherent = false;

			break;

		}

		node = of_get_next_dma_parent(node);

	}

	of_node_put(node);

	return false;

	return is_coherent;

}

EXPORT_SYMBOL_GPL(of_dma_is_coherent);