[Intel-xe] [PATCH] drm/xe: Use Xe BO pin / unpin functions for FB pin

[Matthew Auld]

On Wed, 5 Apr 2023 at 05:19, Matthew Brost <matthew.brost at intel.com> wrote:
>
> Need to use XE BO pin / unpin for suspend / resume to work properly.
> Part this fix too is too allow xe_bo_pin to be called more than once.
>
> Should fix:
> https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/244
>
> Signed-off-by: Matthew Brost <matthew.brost at intel.com>

Change makes sense to me, but I think we also need to update xe_bo_unpin()?

But I must be misunderstanding something here. AFAICT we can have
various pinned VRAM objects, and xe_bo_pin() still adds them to
pinned.kernel_bo_present, where during suspend we evict everything on
that list to system memory. But as these are all still pinned, suspend
is still going to fail with this patch, given the recent TTM changes.
What am I missing?

> ---
>  drivers/gpu/drm/xe/display/xe_fb_pin.c | 4 ++--
>  drivers/gpu/drm/xe/xe_bo.c             | 5 +++--
>  2 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/display/xe_fb_pin.c b/drivers/gpu/drm/xe/display/xe_fb_pin.c
> index 65c0bc28a3d1..c7c849be288f 100644
> --- a/drivers/gpu/drm/xe/display/xe_fb_pin.c
> +++ b/drivers/gpu/drm/xe/display/xe_fb_pin.c
> @@ -205,7 +205,7 @@ static struct i915_vma *__xe_pin_fb_vma(struct intel_framebuffer *fb,
>
>         ret = xe_bo_validate(bo, NULL, true);
>         if (!ret)
> -               ttm_bo_pin(&bo->ttm);
> +               xe_bo_pin(bo);
>         ttm_bo_unreserve(&bo->ttm);
>         if (ret)
>                 goto err;
> @@ -222,7 +222,7 @@ static struct i915_vma *__xe_pin_fb_vma(struct intel_framebuffer *fb,
>
>  err_unpin:
>         ttm_bo_reserve(&bo->ttm, false, false, NULL);
> -       ttm_bo_unpin(&bo->ttm);
> +       xe_bo_unpin(bo);
>         ttm_bo_unreserve(&bo->ttm);
>  err:
>         kfree(vma);
> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> index 3a482c61c3ec..25c696bd380c 100644
> --- a/drivers/gpu/drm/xe/xe_bo.c
> +++ b/drivers/gpu/drm/xe/xe_bo.c
> @@ -1278,8 +1278,8 @@ int xe_bo_pin(struct xe_bo *bo)
>          */
>         XE_BUG_ON(bo->ttm.base.import_attach);
>
> -       /* We only expect at most 1 pin */
> -       XE_BUG_ON(xe_bo_is_pinned(bo));
> +       if (xe_bo_is_pinned(bo))
> +               goto pin;
>
>         err = xe_bo_validate(bo, NULL, false);
>         if (err)
> @@ -1308,6 +1308,7 @@ int xe_bo_pin(struct xe_bo *bo)
>                 }
>         }
>
> +pin:
>         ttm_bo_pin(&bo->ttm);
>
>         /*
> --
> 2.34.1
>