On 9/11/20 4:15 AM, Russell King - ARM Linux admin wrote:
On Thu, Sep 10, 2020 at 07:40:37AM +0200, Christoph Hellwig wrote:
The DMA offset notifier can only be used if PHYS_OFFSET is at least
KEYSTONE_HIGH_PHYS_START, which can't be represented by a 32-bit
phys_addr_t. Currently the code compiles fine despite that, a pending
change to the DMA offset handling would create a compiler warning for
this case. Add an ifdef to not compile the code except for LPAE
configs.
However, to have use of the high physical offset, LPAE needs to be
enabled, which ensures that phys_addr_t is 64-bit.
I believe that DMA is non-coherent on this platform unless the high
physical address is used. Or something like that.
Exactly. Higher address ranges needs to be used for DMA coherency.
Regards,
Santosh
