On Mon, Dec 07, 2009 at 08:55:12PM +0800, figo zhang wrote: > I am writing a driver for MIPS32. i wirte this code for DMA addr: > > dma_vaddr =(char*) __get_free_pages(GFP_KERNEL| > GFP_DMA, order); You probably don't want to use GFP_DMA - unless your hardware has DMA restrictions such as the ISA's bus's 16MB limit. > dma_phy = virt_to_phy(dma_vaddr); Ouch. Don't. See Documentation/DMA-API.txt for how to do it. > i write dma_phy to DMA base register, but why it cannot work? it should > write Kseg1 space to DMA register? > I remember that it is ok for ARM/X86 . It's only happens to work on some systems. Ralf
