[igt-dev] [Intel-gfx] [PATCH i-g-t v2] tests/prime_vgem: Skip basic-read/write subtests if no mappable GGTT

[Janusz Krzysztofik]

Hi Stuart,

On Wednesday, November 20, 2019 11:04:59 PM CET Summers, Stuart wrote:
> On Wed, 2019-11-20 at 17:14 +0000, Summers, Stuart wrote:
> > On Wed, 2019-11-20 at 17:44 +0100, Janusz Krzysztofik wrote:
> > > As we've agreed that using I915_GEM_PREAD/PWRITE IOCTLs on dma-buf
> > > objects doesn't make much sense, we are not going to extend their
> > > handlers in the i915 driver with new processing paths required for
> > > them
> > > to work correctly with dma-buf objects on future hardware with no
> > > mappable aperture.  When running on that kind of hardware, just
> > > skip
> > > subtests which use those IOCTLs.
> > 
> > How is this handled for other dma-buf capable devices? Is there no
> > opportunity for a working solution in i915 here?
> > 
> > Also, is this a permanent limitation? Or just a workaround based on
> > our
> > current implementation?
> 
> Thinking a bit more about this, I think my main concern here is around
> the commit message. You are implying there is no chance we can 

I think my commit message doesn't imply we can't, it says that there is no 
need to ...
> change
> these DRM interfaces to work with dma-buf by referencing an I915 IOCTL.
because that interface is not useful.

> I don't personally have any issue adding the skip below, and honestly
> that seems like a good safeguard. But can you update the commit message
> to indicate that this is simply that, a safeguard, and not because we
> have no option 

As my commit message states, we are not going ...
> to make this work from the kernel side?
even if we have an option, simply because there are no users of such 
interface.

Thanks,
Janusz

> Of course please correct me if I'm mistaken here.
> 
> Thanks,
> Stuart
> 
> > 
> > Thanks,
> > Stuart
> > 
> > > 
> > > Signed-off-by: Janusz Krzysztofik <
> > > janusz.krzysztofik at linux.intel.com
> > > > 
> > > 
> > > Cc: Daniel Vetter <daniel at ffwll.ch>
> > > Cc: Joonas Lahtinen <joonas.lahtinen at intel.com>
> > > ---
> > >  lib/ioctl_wrappers.c | 2 +-
> > >  lib/ioctl_wrappers.h | 1 +
> > >  tests/prime_vgem.c   | 6 ++++++
> > >  3 files changed, 8 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/lib/ioctl_wrappers.c b/lib/ioctl_wrappers.c
> > > index 628f8b83..78b92bd2 100644
> > > --- a/lib/ioctl_wrappers.c
> > > +++ b/lib/ioctl_wrappers.c
> > > @@ -356,7 +356,7 @@ void gem_write(int fd, uint32_t handle,
> > > uint64_t
> > > offset, const void *buf, uint64
> > >  	igt_assert_eq(__gem_write(fd, handle, offset, buf, length), 0);
> > >  }
> > >  
> > > -static int __gem_read(int fd, uint32_t handle, uint64_t offset,
> > > void
> > > *buf, uint64_t length)
> > > +int __gem_read(int fd, uint32_t handle, uint64_t offset, void
> > > *buf,
> > > uint64_t length)
> > >  {
> > >  	struct drm_i915_gem_pread gem_pread;
> > >  	int err;
> > > diff --git a/lib/ioctl_wrappers.h b/lib/ioctl_wrappers.h
> > > index f2412d78..97f278ed 100644
> > > --- a/lib/ioctl_wrappers.h
> > > +++ b/lib/ioctl_wrappers.h
> > > @@ -69,6 +69,7 @@ uint32_t gem_open(int fd, uint32_t name);
> > >  void gem_close(int fd, uint32_t handle);
> > >  int __gem_write(int fd, uint32_t handle, uint64_t offset, const
> > > void
> > > *buf, uint64_t length);
> > >  void gem_write(int fd, uint32_t handle, uint64_t offset,  const
> > > void
> > > *buf, uint64_t length);
> > > +int __gem_read(int fd, uint32_t handle, uint64_t offset, void
> > > *buf,
> > > uint64_t length);
> > >  void gem_read(int fd, uint32_t handle, uint64_t offset, void *buf,
> > > uint64_t length);
> > >  int __gem_set_domain(int fd, uint32_t handle, uint32_t read,
> > > uint32_t write);
> > >  void gem_set_domain(int fd, uint32_t handle, uint32_t read,
> > > uint32_t
> > > write);
> > > diff --git a/tests/prime_vgem.c b/tests/prime_vgem.c
> > > index 04cc913d..6595818c 100644
> > > --- a/tests/prime_vgem.c
> > > +++ b/tests/prime_vgem.c
> > > @@ -46,6 +46,8 @@ static void test_read(int vgem, int i915)
> > >  	handle = prime_fd_to_handle(i915, dmabuf);
> > >  	close(dmabuf);
> > >  
> > > +	igt_skip_on(__gem_read(i915, handle, 0, &i, sizeof(i)));
> > > +
> > >  	ptr = vgem_mmap(vgem, &scratch, PROT_WRITE);
> > >  	for (i = 0; i < 1024; i++)
> > >  		ptr[1024*i] = i;
> > > @@ -81,6 +83,8 @@ static void test_fence_read(int i915, int vgem)
> > >  	handle = prime_fd_to_handle(i915, dmabuf);
> > >  	close(dmabuf);
> > >  
> > > +	igt_skip_on(__gem_read(i915, handle, 0, &i, sizeof(i)));
> > > +
> > >  	igt_fork(child, 1) {
> > >  		close(master[0]);
> > >  		close(slave[1]);
> > > @@ -191,6 +195,8 @@ static void test_write(int vgem, int i915)
> > >  	handle = prime_fd_to_handle(i915, dmabuf);
> > >  	close(dmabuf);
> > >  
> > > +	igt_skip_on(__gem_write(i915, handle, 0, &i, sizeof(i)));
> > > +
> > >  	ptr = vgem_mmap(vgem, &scratch, PROT_READ);
> > >  	gem_close(vgem, scratch.handle);
> > >  
> > 
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