writing pci device driver

Hi I have some question about writing device driver. I am reading some books and text. 1) I have device which have memory space 1 mb. and I mapped this memory using pci_iomap function. I read some text and they said if device need access mapped memory, you set the command register in configuration space. But which bit will ve set? only is enough only bit set PCI_COMMAND_MEMORY<http://lxr.linux.no/linux+*/+code=PCI_COMMAND_MEMORY> ? 2) I dont want to use dma first step. Maybe next time I will be use. PCI_COMMAND_MASTER <http://lxr.linux.no/linux+*/+code=PCI_COMMAND_MASTER> this command bit is only set when I use dma ? is it true? thanks.