On Mon, 13 Mar 2023 21:28:28 +0900, "Chan Kim" said:
which is 32-bit addressable. Even if the device indicates (via the DMA mask) that it may address the upper 32-bits, consistent allocation will only return > 32-bit addresses for DMA if the consistent DMA mask has been explicitly changed via dma_set_coherent_mask(). This is true of the dma_pool interface as well. ------------------------------
By context I guess it returns the address in lower 32bit address range even it the coherent_dma_mask is set to some bigger value.
No, you have that backwards. It's not "even if". It wil give you a 32-bit address *UNLESS* the driver has called dma_set_coherent_mask() to set a wider mask *and* the device indicates it supports more than 32 bit addresses...