of: Add OF_DMA_DEFAULT_COHERENT & select it on powerpc (dabf6b36) · Commits · 戴 / test

There's an OF helper called of_dma_is_coherent(), which checks if a device has a "dma-coherent" property to see if the device is coherent for DMA. But on some platforms devices are coherent by default, and on some platforms it's not possible to update existing device trees to add the "dma-coherent" property. So add a Kconfig symbol to allow arch code to tell of_dma_is_coherent() that devices are coherent by default, regardless of the presence of the property. Select that symbol on powerpc when NOT_COHERENT_CACHE is not set, ie. when the system has a coherent cache. Fixes: ("of: introduce of_dma_is_coherent() helper") Cc: stable@vger.kernel.org # v3.16+ Reported-by:

Christian Zigotzky <chzigotzky@xenosoft.de> Tested-by:

Christian Zigotzky <chzigotzky@xenosoft.de> Signed-off-by:

Michael Ellerman <mpe@ellerman.id.au> Reviewed-by:

Ulf Hansson <ulf.hansson@linaro.org> Signed-off-by:

Rob Herring <robh@kernel.org>

arch/powerpc/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -238,6 +238,7 @@ config PPC
		select NEED_DMA_MAP_STATE if PPC64 \|\| NOT_COHERENT_CACHE
		select NEED_SG_DMA_LENGTH
		select OF
		select OF_DMA_DEFAULT_COHERENT if !NOT_COHERENT_CACHE
		select OF_EARLY_FLATTREE
		select OLD_SIGACTION if PPC32
		select OLD_SIGSUSPEND

drivers/of/Kconfig

+4 −0

Original line number	Diff line number	Diff line
		@@ -103,4 +103,8 @@ config OF_OVERLAY
		config OF_NUMA
		bool

		config OF_DMA_DEFAULT_COHERENT
		# arches should select this if DMA is coherent by default for OF devices
		bool

		endif # OF

drivers/of/address.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -995,12 +995,16 @@ out:
		* @np: device node
		*
		* It returns true if "dma-coherent" property was found
		* for this device in DT.
		* for this device in the DT, or if DMA is coherent by
		* default for OF devices on the current platform.
		*/
		bool of_dma_is_coherent(struct device_node *np)
		{
		struct device_node *node = of_node_get(np);

		if (IS_ENABLED(CONFIG_OF_DMA_DEFAULT_COHERENT))
		return true;

		while (node) {
		if (of_property_read_bool(node, "dma-coherent")) {
		of_node_put(node);

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