On 29/07/2021 00:07, Dixit, Ashutosh wrote:
On Wed, 28 Jul 2021 03:30:34 -0700, Matthew Auld wrote:diff --git a/lib/i915/gem_mman.c b/lib/i915/gem_mman.c index 337d28fb..6f5e6d72 100644 --- a/lib/i915/gem_mman.c +++ b/lib/i915/gem_mman.c @@ -434,7 +434,13 @@ void *gem_mmap__device_coherent(int fd, uint32_t handle, uint64_t offset, */ void *__gem_mmap__cpu(int fd, uint32_t handle, uint64_t offset, uint64_t size, unsigned prot) { - return __gem_mmap(fd, handle, offset, size, prot, 0); + void *ptr; + + ptr = __gem_mmap(fd, handle, offset, size, prot, 0); + if (!ptr) + ptr = __gem_mmap_offset__fixed(fd, handle, offset, size, prot); + + return ptr;What about __gem_mmap__wc? Also shouldn't we just fix the __gem_mmap_offset fallback in __gem_mmap and that will take care of both __gem_mmap__cpu and __gem_mmap__wc?
For gem_mmap__wc it felt like slightly too much lying, since on discrete smem-only buffers are always wb, and so the __wc here is not what the user gets with the new FIXED mode. gem_mmap__device_coherent() I think matches this new behaviour well, where we don't explicitly state what the mapping type is, but instead just guarantee that the returned mapping is device coherent. My rough thinking was to convert most users of __wc over to __device_coherent(), at least in the tests that we care about for discrete?
On the other hand if we are happy with the lie, I don't think anything will break, and pretty much all testscases using mmap I think should just magically work on discrete, and it does mean a less less work vs converting to __device_coherent?
(I think it will actually also fix __gem_mmap__device_coherent and __gem_mmap__cpu_coherent but maybe we can still have those patches in this series especially if they save a couple of system calls).
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