On Wed, 27 Oct 2021 at 09:36, Thomas Hellström
<thomas.hellstrom@xxxxxxxxxxxxxxx> wrote:
>
> GPU relocs are gone. There should be no need for this workaround anymore.
> Remove it.
>
> Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
I was completely wrong here, sorry. Digging through the git history it
looks like this came from:
Commit 149c84077fe717af883bae459623ef1cebd86388
Author: Daniel Vetter <daniel.vetter@xxxxxxxx>
Date: Wed Feb 15 23:50:23 2012 +0100
drm/i915: implement SNB workaround for lazy global gtt
PIPE_CONTROL on snb needs global gtt mappings in place to workaround a
hw gotcha. No other commands need such a workaround. Luckily we can
detect a PIPE_CONTROL commands easily because they have a write_domain
= I915_GEM_DOMAIN_INSTRUCTION (and nothing else has that).
so it looks to be unrelated to GPU relocs, which AFAIK didn't exist at
the time. I just saw the MI comment and assumed it was talking about
the MI_STORE_DWORD...
> ---
> .../gpu/drm/i915/gem/i915_gem_execbuffer.c | 19 +------------------
> 1 file changed, 1 insertion(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> index 1231224728e4..04af88e6d453 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> @@ -1327,7 +1327,6 @@ eb_relocate_entry(struct i915_execbuffer *eb,
> {
> struct drm_i915_private *i915 = eb->i915;
> struct eb_vma *target;
> - int err;
>
> /* we've already hold a reference to all valid objects */
> target = eb_get_vma(eb, reloc->target_handle);
> @@ -1357,25 +1356,9 @@ eb_relocate_entry(struct i915_execbuffer *eb,
> return -EINVAL;
> }
>
> - if (reloc->write_domain) {
> + if (reloc->write_domain)
> target->flags |= EXEC_OBJECT_WRITE;
>
> - /*
> - * Sandybridge PPGTT errata: We need a global gtt mapping
> - * for MI and pipe_control writes because the gpu doesn't
> - * properly redirect them through the ppgtt for non_secure
> - * batchbuffers.
> - */
> - if (reloc->write_domain == I915_GEM_DOMAIN_INSTRUCTION &&
> - GRAPHICS_VER(eb->i915) == 6) {
> - err = i915_vma_bind(target->vma,
> - target->vma->obj->cache_level,
> - PIN_GLOBAL, NULL);
> - if (err)
> - return err;
> - }
> - }
> -
> /*
> * If the relocation already has the right value in it, no
> * more work needs to be done.
> --
> 2.31.1
>
