On Sat, Jan 29, 2005 at 03:00:23PM +0000, Christoph Hellwig wrote: > Either way a new driver shouldn't use isa_virt_to_bus at all but rather > use the proper DMA API and all those problems go away.
One thing which comes up in this instance is: what struct device should be used. With ISA devices doing DMA, the device which actually "owns" the DMA is the ISA DMA controller, not the device wiggling its DMA request signal to the ISA DMA controller. Given that, shouldn't the ISA DMA code have its own struct device to represent the ISA DMA engine for things like the floppy driver and other drivers using the ISA DMA engine? To me, it makes no sense to pass the ISA device wiggling its DMA request into the DMA API - this ISA device doesn't care whether the ISA DMA engine can only access the first 16MB of memory or not (which is ISA DMA engine specific), so the DMA mask on the ISA device is rather meaningless. (This type of DMA also appears on later ARM platforms as well, hence why I have given the whole issue some thought.) -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/ 2.6 Serial core - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
