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. Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx> --- drivers/of/address.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/drivers/of/address.c b/drivers/of/address.c index 94f017d808c4..1c362d09983d 100644 --- a/drivers/of/address.c +++ b/drivers/of/address.c @@ -1045,26 +1045,32 @@ 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; + bool ret = false; if (IS_ENABLED(CONFIG_OF_DMA_DEFAULT_COHERENT)) - return true; + ret = true; node = of_node_get(np); while (node) { if (of_property_read_bool(node, "dma-coherent")) { - of_node_put(node); - return true; + ret = true; + break; + } + if (of_property_read_bool(node, "dma-noncoherent")) { + ret = false; + break; } node = of_get_next_dma_parent(node); } of_node_put(node); - return false; + return ret; } EXPORT_SYMBOL_GPL(of_dma_is_coherent); -- 2.35.1