Pinning lots of small buffer objects, such as cursors or sprites, to video memory can lead to fragmentation, which is a problem for devices with only a small amount of memory. As a result, framebuffer images might not get pinned, even though there's enough space available overall.
The flag DRM_GEM_VRAM_PL_FLAG_TOPDOWN marks buffer objects to be pinned at the high end of video memory. This leaves contiguous space available at the memory's low end.
Signed-off-by: Thomas Zimmermann tzimmermann@suse.de --- drivers/gpu/drm/drm_gem_vram_helper.c | 14 ++++++++++---- include/drm/drm_gem_vram_helper.h | 1 + 2 files changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c index 49588de88959..91baf3f279f1 100644 --- a/drivers/gpu/drm/drm_gem_vram_helper.c +++ b/drivers/gpu/drm/drm_gem_vram_helper.c @@ -58,6 +58,7 @@ static void drm_gem_vram_placement(struct drm_gem_vram_object *gbo, { unsigned int i; unsigned int c = 0; + u32 invariant_flags = pl_flag & TTM_PL_FLAG_TOPDOWN;
gbo->placement.placement = gbo->placements; gbo->placement.busy_placement = gbo->placements; @@ -65,15 +66,18 @@ static void drm_gem_vram_placement(struct drm_gem_vram_object *gbo, if (pl_flag & TTM_PL_FLAG_VRAM) gbo->placements[c++].flags = TTM_PL_FLAG_WC | TTM_PL_FLAG_UNCACHED | - TTM_PL_FLAG_VRAM; + TTM_PL_FLAG_VRAM | + invariant_flags;
if (pl_flag & TTM_PL_FLAG_SYSTEM) gbo->placements[c++].flags = TTM_PL_MASK_CACHING | - TTM_PL_FLAG_SYSTEM; + TTM_PL_FLAG_SYSTEM | + invariant_flags;
if (!c) gbo->placements[c++].flags = TTM_PL_MASK_CACHING | - TTM_PL_FLAG_SYSTEM; + TTM_PL_FLAG_SYSTEM | + invariant_flags;
gbo->placement.num_placement = c; gbo->placement.num_busy_placement = c; @@ -236,7 +240,9 @@ static int drm_gem_vram_pin_locked(struct drm_gem_vram_object *gbo, * a memory region. A pinned buffer object has to be unpinned before * 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). + * memory). The modifier DRM_GEM_VRAM_PL_FLAG_TOPDOWN marks the buffer + * object to be pinned at the high end of the memory region. Set this + * flag to avoid memory fragmentation. * * Returns: * 0 on success, or diff --git a/include/drm/drm_gem_vram_helper.h b/include/drm/drm_gem_vram_helper.h index 418eb1122861..354a9cd358a3 100644 --- a/include/drm/drm_gem_vram_helper.h +++ b/include/drm/drm_gem_vram_helper.h @@ -19,6 +19,7 @@ struct vm_area_struct;
#define DRM_GEM_VRAM_PL_FLAG_VRAM TTM_PL_FLAG_VRAM #define DRM_GEM_VRAM_PL_FLAG_SYSTEM TTM_PL_FLAG_SYSTEM +#define DRM_GEM_VRAM_PL_FLAG_TOPDOWN TTM_PL_FLAG_TOPDOWN
/* * Buffer-object helpers