Re: [igt-dev] [PATCH i-g-t 4/9] tests/prime_mmap: use device coherent mapping instead of mmap_gtt

Dixit, Ashutosh
2020-02-01T06:57:31Z

On Fri, 31 Jan 2020 09:31:04 -0800, Ramalingam C wrote:
>
> Since on new discrete GPUs we dont have the mappable aperture, if that
> is acceptable for the test purpose, we should use GEM_MMAP_OFFSET.
> Hence using gem_mmap_device_coherent() which wraps the mmap options in
> the order of gem_mmap_offset / gem_mmap / mmap_gtt
>
> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
> ---
> tests/prime_mmap.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tests/prime_mmap.c b/tests/prime_mmap.c
> index fc985784407b..1433424109c8 100644
> --- a/tests/prime_mmap.c
> +++ b/tests/prime_mmap.c
> @@ -85,8 +85,8 @@ test_correct(void)
> dma_buf_fd = prime_handle_to_fd(fd, handle);
> igt_assert(errno == 0);
>
> - /* Check correctness vs GEM_MMAP_GTT */
> - ptr1 = gem_mmap__gtt(fd, handle, BO_SIZE, PROT_READ);
> + /* Check correctness vs GEM_MMAP */
> + ptr1 = gem_mmap__device_coherent(fd, handle, 0, BO_SIZE, PROT_READ);

Once again, does this test pass with gtt mapping but fail with wc mapping?
I thought gtt mapping also bypasses the cache like wc? What about prime
mmap's? Can someone please confirm? Otherwise I will try to look.