Re: [alsa-devel] [PATCH] ASoC drivers for the Freescale MPC8610 SoC

Lee Revell wrote:

Please use DMA_32BIT_MASK (see include/linux/dma-mapping.h) instead of 0xffffffff.

No prob. But did you see this comment:

/* * NOTE: do not use the below macros in new code and do not add new definitions * here. * * Instead, just open-code DMA_BIT_MASK(n) within your driver */

So I guess I should use DMA_BIT_MASK(32) instead.

I've personally fixed a heisenbug in an ALSA driver caused by incorrectly typed DMA mask...

Can you explain to me what all of this does? Is it okay to use a static u64 variable? Why do so many drivers do it that way? I don't even know if 0xFFFFFFFF is the right number for my platform.