Messages in this thread |  | | From | Oded Gabbay <> | | Date | Fri, 1 Apr 2022 14:31:12 +0300 | | Subject | Re: [PATCH] habanalabs: fix build warning |
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On Fri, Apr 1, 2022 at 10:53 AM Arnd Bergmann <arnd@arndb.de> wrote: > > On Fri, Apr 1, 2022 at 8:55 AM Oded Gabbay <ogabbay@kernel.org> wrote: > > On Fri, Apr 1, 2022 at 9:40 AM Arnd Bergmann <arnd@arndb.de> wrote: > > > On Fri, Apr 1, 2022 at 6:16 AM Max Filippov <jcmvbkbc@gmail.com> wrote: > > > > We use gen_pool in this function to manage our device memory > > allocations (this is why it is called alloc_device_memory). > > Ok, so it's none of the three I listed ;-) > > > Basically, we initialize the genpool with the total size of the device memory, > > and each bit represents a page according to a fixed page size, which > > is dependent on asic type. > > The addresses represent the physical address of the device memory, as > > our device sees them. > > As these addresses are not accessible from the host, it is appropriate > > to hold them in u64, imo. > > > > For future asics which will support multiple page sizes, we need to > > use the gen_pool_dma_alloc_align() variant, > > because then we need the allocation to be aligned to the page size as > > requested by the user per allocation. > > > > We ignore the DMA address because this is device memory, not host memory. > > Therefore, our device's dma engine addresses the memory using the > > virtual memory addresses we assign to it in our device's MMU. > > > > Having said that, I'm wondering whether gen_pool_first_fit_align() can > > also work here, which might be less confusing. > > Thank you for the explanation. I think the best way to make this less > confusing and to avoid the type casts would be to define your own > typedef for a device-internal address, and then wrap the allocator > functions such as gen_pool_dma_alloc_align() in helper functions that > do the type conversion safely. > > Arnd
Thanks for the advice, we will prepare a patch accordingly. Oded
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