On Thu, Sep 05, 2019 at 07:05:43PM +0200, Thomas Hellström (VMware) wrote: > I took a quick look at the interfaces and have two questions: > > 1) dma_mmap_prepare(), would it be possible to drop the references to the > actual coherent region? The thing is that TTM doesn't know at mmap time what > memory will be backing the region. It can be VRAM, coherent memory or system
I guess we can shift the argument checking into the fault handler. > 2) @cpu_addr and @dma_addr are the values pointing at the beginning of an > allocated chunk, right? Yes. > The reason I'm asking is that TTM's coherent memory > pool is sub-allocating from larger chunks into smaller PAGE_SIZE chunks, > which means that a TTM buffer object may be randomly split across larger > chunks, which means we have to store these values for each PAGE_SiZE chunk. For implementations that remap non-contigous regions using vmap we need the start cpu address passed, as that is used to find the vm_struct structure for it. That being said I don't see a problem with you keeping track of the original start and offset into in your suballocation helpers.
