On Tue, Jun 11, 2019 at 03:03:36PM +0200, Thomas Zimmermann wrote:
> Pinning a buffer prevents it from being moved to a different memory
> location. For some operations, such as buffer updates, it is not
> important where the buffer is located. Setting the pin function's
> pl_flag argument to 0 will pin the buffer to whereever it is stored.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
> ---
> drivers/gpu/drm/drm_gem_vram_helper.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
> index 42ad80888df7..214f54b8920b 100644
> --- a/drivers/gpu/drm/drm_gem_vram_helper.c
> +++ b/drivers/gpu/drm/drm_gem_vram_helper.c
> @@ -224,7 +224,9 @@ EXPORT_SYMBOL(drm_gem_vram_offset);
> *
> * Pinning a buffer object ensures that it is not evicted from
> * a memory region. A pinned buffer object has to be unpinned before
> - * it can be pinned to another region.
> + * it can be pinned to another region. If the pl_flag argument is 0,
> + * the buffer is pinned at its current location (video RAM or system
> + * memory).
> *
> * Returns:
> * 0 on success, or
> @@ -242,7 +244,9 @@ int drm_gem_vram_pin(struct drm_gem_vram_object *gbo, unsigned long pl_flag)
> if (gbo->pin_count)
> goto out;
>
> - drm_gem_vram_placement(gbo, pl_flag);
> + if (pl_flag)
> + drm_gem_vram_placement(gbo, pl_flag);
> +
> for (i = 0; i < gbo->placement.num_placement; ++i)
> gbo->placements[i].flags |= TTM_PL_FLAG_NO_EVICT;
>
> @@ -691,7 +695,7 @@ int drm_gem_vram_driver_gem_prime_pin(struct drm_gem_object *gem)
> {
> struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
>
> - return drm_gem_vram_pin(gbo, DRM_GEM_VRAM_PL_FLAG_VRAM);
> + return drm_gem_vram_pin(gbo, 0);
Not sure this is a good idea here. If the bo happens to be in sysram
it can't be displayed any more.
> - ret = drm_gem_vram_pin(gbo, DRM_GEM_VRAM_PL_FLAG_VRAM);
> + ret = drm_gem_vram_pin(gbo, 0);
Likewise.
cheers,
Gerd
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