of: Add OF_DMA_DEFAULT_COHERENT & select it on powerpc
authorMichael Ellerman <mpe@ellerman.id.au>
Sun, 26 Jan 2020 11:52:47 +0000 (22:52 +1100)
committerRob Herring <robh@kernel.org>
Tue, 28 Jan 2020 14:26:20 +0000 (08:26 -0600)
commitdabf6b36b83a18d57e3d4b9d50544ed040d86255
treebe02aaf9a02b27d300c787643a913c1a4ae0270d
parent9243f296916794d86dfcabd802b4dac1ac1448a9
of: Add OF_DMA_DEFAULT_COHERENT & select it on powerpc

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")
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
drivers/of/Kconfig
drivers/of/address.c