3.16.84-rc1 review patch. If anyone has any objections, please let me know.
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From: Michael Ellerman mpe@ellerman.id.au
commit dabf6b36b83a18d57e3d4b9d50544ed040d86255 upstream.
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: 92ea637edea3 ("of: introduce of_dma_is_coherent() helper") 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 [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- arch/powerpc/Kconfig | 1 + drivers/of/Kconfig | 4 ++++ drivers/of/address.c | 6 +++++- 3 files changed, 10 insertions(+), 1 deletion(-)
--- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -89,6 +89,7 @@ config PPC select ARCH_MIGHT_HAVE_PC_SERIO select BINFMT_ELF select OF + select OF_DMA_DEFAULT_COHERENT if !NOT_COHERENT_CACHE select OF_EARLY_FLATTREE select OF_RESERVED_MEM select HAVE_FTRACE_MCOUNT_RECORD --- a/drivers/of/Kconfig +++ b/drivers/of/Kconfig @@ -78,4 +78,8 @@ config OF_RESERVED_MEM help Helpers to allow for reservation of memory regions
+config OF_DMA_DEFAULT_COHERENT + # arches should select this if DMA is coherent by default for OF devices + bool + endmenu # OF --- a/drivers/of/address.c +++ b/drivers/of/address.c @@ -812,12 +812,16 @@ EXPORT_SYMBOL_GPL(of_dma_get_range); * @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);