Messages in this thread | | | Date | Fri, 11 Sep 2020 12:15:51 +0100 | From | Russell King - ARM Linux admin <> | Subject | Re: [PATCH 2/3] ARM/keystone: move the DMA offset handling under ifdef CONFIG_ARM_LPAE |
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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.
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