ARM: dma-mapping: fix for speculative prefetching
(Russell's patch regarding speculative prefetching)
Cortex-A9 Technical Reference Manual: 6.5.2. Data prefetching and monitoring
The Cortex-A9 data cache implements an automatic prefetcher that monitors cache misses done by the processor. This unit can monitor and prefetch two independent data streams. It can be activated in software using a CP15 Auxiliary Control Register bit. See Auxiliary Control Register.
When the software issues a PLD instruction the PLD prefetch unit always takes precedence over requests from the data prefetch mechanism. Prefetched lines in the speculative prefetcher can be dropped before they are allocated. PLD instructions are always executed and never dropped.
PLD, PLDW, and PLI
(seems on armv4l, not related to speculative prefetching)