* Russell King <[email protected]> [120418 03:14]: > Using coherent DMA memory with the OMAP DMA engine results in > unpredictable behaviour due to memory ordering issues; as things stand, > there is no guarantee that data written to coherent DMA memory will be > visible to the DMA hardware. > > This is because the OMAP dma_write() accessor contains no barriers, > necessary on ARMv6 and above. The effect of this can be seen in comments > in the OMAP serial driver, which incorrectly talks about cache flushing > for the coherent DMA stuff. > > Rather than adding barriers to the accessors, add it in the DMA support > code just before we enable DMA, and just after we disable DMA. This > avoids having barriers for every DMA register access. > > Signed-off-by: Russell King <[email protected]>
Acked-by: Tony Lindgren <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
