[igt-dev] [PATCH i-g-t v3] lib/i915/gem_mman: Add a helper for obtaining mappable aperture version

[Chris Wilson]

Quoting Janusz Krzysztofik (2019-05-31 09:33:38)
> From: Janusz Krzysztofik <janusz.krzysztofik at intel.com>
> 
> If a test calls a function which depends on availabiblity of a
> supported mappable aperture, an error may be reported by the kernel on
> unsupported hardware.  That may negatively affect results reported by a
> test framework even if that test ignores the failure and succeedes.
> 
> This helper wraps an IOCTL call which returns a version number of a
> mappable aperture.  It may be used by tests which need to adjust their
> scope depending on availability of specific version of mappable
> aperture.
> 
> Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at intel.com>
> Cc: Antonio Argenziano <antonio.argenziano at intel.com>
> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> ---
> Changelog:
> v2 (internal) -> v3:
> - make the code less obsucre, more explicit (Antonio),
> - reword the helper documentation and commit message.
> 
> v1 (internal) -> v2 (internal):
> - minimize future potential conflicts with 
>   https://patchwork.freedesktop.org/patch/294053/?series=58551&rev=1
>   (no progress with than one so not waiting for it any longer):
>   - convert the helper to a drop-in replacement of the one from the
>     above mentioned patch, returning mappable aperture version, not
>     only information on its availability,
>   - drop any other wrappers,
> - document the helper,
> - reword commit message.
> 
>  lib/i915/gem_mman.c | 22 ++++++++++++++++++++++
>  lib/i915/gem_mman.h |  1 +
>  2 files changed, 23 insertions(+)
> 
> diff --git a/lib/i915/gem_mman.c b/lib/i915/gem_mman.c
> index 3cf9a6bb..3a3f3e5c 100644
> --- a/lib/i915/gem_mman.c
> +++ b/lib/i915/gem_mman.c
> @@ -40,6 +40,28 @@
>  #define VG(x) do {} while (0)
>  #endif
>  
> +/**
> + * gem_mmap__gtt_version:
> + * @fd: open i915 drm file descriptor
> + *
> + * This functions wraps up an IOCTL to obtain mappable aperture version.
> + *
> + * Returns: mappable aperture version, -1 on failure.
> + */
> +int gem_mmap__gtt_version(int fd)
> +{
> +       int gtt_version, ret;
> +       struct drm_i915_getparam gp = {
> +               .param = I915_PARAM_MMAP_GTT_VERSION,
> +               .value = &gtt_version,
> +       };
> +
> +       ret = ioctl(fd, DRM_IOCTL_I915_GETPARAM, &gp);
> +       if (ret == 0)
> +               ret = gtt_version;
> +       return ret;

Maybe the actual error returned by the kernel and not glibc would be
interesting in the future?
-Chris