randy_dunlap wrote: >+The DMA:able address space is the lowest 16 MB of _physical_ memory. > The DMA-able >+Also the transfer block may not cross page boundaries (which are 64k). > I would write: (which are 64 KB). > >if I knew that was correct, but I don't. >Does Linux limit all ISA-DMA to not crossing 64 KB boundaries? >I haven't looked at the code yet, just PC-AT Technical Reference, >which says that DMA controller 1 is limited to 8-bit transfers and >64 KB blocks and DMA controller 2 is limited to 16-bit data transfers >and 128 KB boundaries. >Does i386-compatible and later chipsets or LPC change/affect this? >(I see that you cover 8/16-bit transfers later in the doc.) > >
Sorry, my bad. 128k is quite correct for 16-bit data transfers. I've just been using 8-bit transfers so I got a bit too familiar with just those. :) >+To translate the virtual address to a physical use the normal DMA >+API. Do _not_ use isa_virt_to_phys() even though it does the same >+thing. The reason for this is that you will get a requirement to ISA >+(instead of only ISA_DMA_API). > >I don't understand what you are trying to say in: >... is that you will get a requirement to ISA.... >Oh, it's Kconfig-related, right? So maybe: >"... is that you will get a config requirement for ISA..." ? > > > Yes, that's what I'm trying to say. I'll try to make it clearer. Thanks for the feedback. I'll get your suggestions in and post a new patch. Rgds Pierre - 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/
