Re: dma_mask limited to 32-bits with OF platform device

On Wed, Feb 12, 2020 at 02:04:31PM +0000, Robin Murphy wrote:

quoted

For now, let's say that we limit dma-ranges to 4GB size. with "dma-ranges 
= <0x00000000 0x00000000 0x1 0x00000000>;"
Then, dma_bus_limit is set correctly to 0xffffffff, SATA driver sets masks 
to 64-bit as IP supports that.

[   13.306847] ahci 4a140000.sata: dma_mask 0xffffffffffffffff, 
coherent_mask 0xffffffffffffffff, dma_bus_limit 0xffffffff

However, the SATA controller still tries to do DMA above 32-bits.
dma_alloc() doesn't seem to be taking dma_bus_limit into account?

Yay ARM LPAE... Peter and Christoph have already been playing whack-a-mole 
with other bugs under that config - is this with or without SWIOTLB? (and 
whichever way, does the other work any better?)

Hmm.  ARM LPAE still uses the arm legacy dma alloc coherent, and that
might not be taking the dma_bus_limit into account.  Let me check..