[igt-dev] [i-g-t] lib/i915: Use FIXED mapping only for discrete memory

[Petri Latvala]

On Fri, Aug 27, 2021 at 06:30:02PM +0530, Tejas Upadhyay wrote:
> The FIXED mapping is only used for discrete, and mapping type
> is pre-defined. This disables the other type of mmap
> offsets when discrete memory is used.
> 
> Taken from kernel commit:
> commit 7961c5b60f23 ("drm/i915: Add TTM offset argument to mmap.")
> 
> Signed-off-by: Tejas Upadhyay <tejaskumarx.surendrakumar.upadhyay at intel.com>
> ---
>  include/drm-uapi/i915_drm.h | 1 +
>  lib/i915/gem_mman.c         | 8 +++++++-
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/include/drm-uapi/i915_drm.h b/include/drm-uapi/i915_drm.h
> index a1c0030c..b46367f2 100644
> --- a/include/drm-uapi/i915_drm.h
> +++ b/include/drm-uapi/i915_drm.h
> @@ -871,6 +871,7 @@ struct drm_i915_gem_mmap_offset {
>  #define I915_MMAP_OFFSET_WC  1
>  #define I915_MMAP_OFFSET_WB  2
>  #define I915_MMAP_OFFSET_UC  3
> +#define I915_MMAP_OFFSET_FIXED 4
>  
>  	/*
>  	 * Zero-terminated chain of extensions.
> diff --git a/lib/i915/gem_mman.c b/lib/i915/gem_mman.c
> index 0406a0b9..1917c24d 100644
> --- a/lib/i915/gem_mman.c
> +++ b/lib/i915/gem_mman.c
> @@ -75,7 +75,13 @@ bool gem_has_legacy_mmap(int fd)
>  
>  bool gem_has_mmap_offset_type(int fd, const struct mmap_offset *t)
>  {
> -	return gem_has_mmap_offset(fd) || t->type == I915_MMAP_OFFSET_GTT;
> +	if (gem_has_mmap_offset(fd))
> +		if (!gem_has_lmem(fd))
> +			return !(t->type == I915_MMAP_OFFSET_FIXED);
> +		else
> +			return !(t->type != I915_MMAP_OFFSET_FIXED);

Why the !(a == b) stuff?
       ^^^


-- 
Petri Latvala