Re: [patch] kconfig: unify GENERIC_ISA_DMA and ISA_DMA_API

On Wed, 26 Jan 2011, Russell King - ARM Linux wrote:

On Tue, Jan 25, 2011 at 05:06:28PM -0800, David Rientjes wrote:

quoted

CONFIG_GENERIC_ISA_DMA and CONFIG_ISA_DMA_API usually have dependencies
on one another depending on the architecture and generic kernel code uses
either to determine whether an ISA-style DMA API is configured.

Wrong.

GENERIC_ISA_DMA enables support for the standard ISA DMA allocator found
in kernel/dma.c

ISA_DMA_API says that a platform supports the ISA DMA interfaces.

An architecture can provide the ISA DMA interfaces, but not use the
standard ISA DMA allocator found in kernel/dma.c.  Such as the one in
arch/arm/kernel/dma.c.

So on ARM, we have platforms where ISA_DMA_API=y but GENERIC_ISA_DMA=n.

Ok, fair enough.  Thanks for pointing that out.  I'll work to resolve the 
existing dependency chain on x86 that cause build failures when one is 
disabled and another is not and add Kconfig dependencies on drivers that 
require GENERIC_ISA_DMA.