On Tue, Jun 14, 2011 at 12:30:44AM +0900, KyongHo Cho wrote: > On Tue, Jun 14, 2011 at 12:07 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > > I'm sure that the graphics people will disagree with you on that. > > Having the frame buffer mapped in write-combine mode is rather > > important when you want to efficiently output videos from your > > CPU. > > I agree with you. > But I am discussing about dma_alloc_writecombine() in ARM. > You can see that only ARM and AVR32 implement it and there are few > drivers which use it. > No function in dma_map_ops corresponds to dma_alloc_writecombine(). > That's why Marek tried to add 'alloc_writecombine' to dma_map_ops. FWIW, on ARMv6 and later hardware, the dma_alloc_coherent() provides writecombine memory (i.e. Normal Noncacheable), so no need for dma_alloc_writecombine(). On earlier architectures it is creating Strongly Ordered mappings (no writecombine). -- Catalin -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>