diff mbox

drm/ttm: Don't move non-existing data

Message ID 1384759838-3501-1-git-send-email-thellstrom@vmware.com (mailing list archive)
State New, archived
Headers show

Commit Message

Thomas Hellstrom Nov. 18, 2013, 7:30 a.m. UTC
If ttm_bo_move_memcpy was instructed to move a non-populated ttm to
io memory, it would first populate the ttm, then move the data and then
destroy the ttm. That's stupid. However, some drivers might have relied on
this to clear io memory from old stuff. So instead of a NOP, which would
be the most efficient, just clear the destination.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
 drivers/gpu/drm/ttm/ttm_bo_util.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

Comments

Jakob Bornecrantz Nov. 18, 2013, 11:38 a.m. UTC | #1
----- Original Message -----
> If ttm_bo_move_memcpy was instructed to move a non-populated ttm to
> io memory, it would first populate the ttm, then move the data and then
> destroy the ttm. That's stupid. However, some drivers might have relied on
> this to clear io memory from old stuff. So instead of a NOP, which would
> be the most efficient, just clear the destination.
> 
> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>

Reviewed-by: Jakob Bornecrantz <jakob@vmware.com>

Cheers, Jakob.

> ---
>  drivers/gpu/drm/ttm/ttm_bo_util.c |    7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c
> b/drivers/gpu/drm/ttm/ttm_bo_util.c
> index 4834c46..15b86a9 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> @@ -350,10 +350,13 @@ int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
>  		goto out2;
>  
>  	/*
> -	 * Move nonexistent data. NOP.
> +	 * Don't move nonexistent data. Clear destination instead.
>  	 */
> -	if (old_iomap == NULL && ttm == NULL)
> +	if (old_iomap == NULL &&
> +	    (ttm == NULL || ttm->state == tt_unpopulated)) {
> +		memset_io(new_iomap, 0, new_mem->num_pages*PAGE_SIZE);
>  		goto out2;
> +	}
>  
>  	/*
>  	 * TTM might be null for moves within the same region.
> --
> 1.7.10.4
>
diff mbox

Patch

diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index 4834c46..15b86a9 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -350,10 +350,13 @@  int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
 		goto out2;
 
 	/*
-	 * Move nonexistent data. NOP.
+	 * Don't move nonexistent data. Clear destination instead.
 	 */
-	if (old_iomap == NULL && ttm == NULL)
+	if (old_iomap == NULL &&
+	    (ttm == NULL || ttm->state == tt_unpopulated)) {
+		memset_io(new_iomap, 0, new_mem->num_pages*PAGE_SIZE);
 		goto out2;
+	}
 
 	/*
 	 * TTM might be null for moves within the same region.