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

Ramalingam C
2020-02-02T18:28:09Z

On 2020-01-31 at 22:57:29 -0800, Dixit, Ashutosh wrote:
> 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.
Ashutosh,

At this test subtest test-correct is failing at gem_mmap__gtt, but
passes when we use device coherent mapping.

-Ram