From: Thierry Reding treding@nvidia.com

Buffer mappings used in job submissions are usually small and not rapidly reused as opposed to framebuffers (which are usually large and rapidly reused, for example when page-flipping between double-buffered framebuffers). Avoid going through the mapping cache for these buffers since the cache would also lead to leaks if nobody is ever releasing the cache's last reference. For DRM/KMS these last references are dropped when the framebuffers are removed and therefore no longer needed.

While at it, also add a note about the need to explicitly remove the final reference to the mapping in the cache.

Signed-off-by: Thierry Reding treding@nvidia.com --- drivers/gpu/host1x/job.c | 4 ++-- include/linux/host1x.h | 5 +++++ 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/host1x/job.c b/drivers/gpu/host1x/job.c index 9424b3c08ab2..f81f3b9f7510 100644 --- a/drivers/gpu/host1x/job.c +++ b/drivers/gpu/host1x/job.c @@ -176,7 +176,7 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) goto unpin; }

- map = host1x_bo_pin(dev, bo, direction, &client->cache); + map = host1x_bo_pin(dev, bo, direction, NULL); if (IS_ERR(map)) { host1x_bo_put(bo); err = PTR_ERR(map); @@ -226,7 +226,7 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job) goto unpin; }

- map = host1x_bo_pin(host->dev, g->bo, DMA_TO_DEVICE, &host->cache); + map = host1x_bo_pin(host->dev, g->bo, DMA_TO_DEVICE, NULL); if (IS_ERR(map)) { host1x_bo_put(g->bo); err = PTR_ERR(map); diff --git a/include/linux/host1x.h b/include/linux/host1x.h index e8dc5bc41f79..46081afd0ca0 100644 --- a/include/linux/host1x.h +++ b/include/linux/host1x.h @@ -31,6 +31,11 @@ u64 host1x_get_dma_mask(struct host1x *host1x); * struct host1x_bo_cache - host1x buffer object cache * @mappings: list of mappings * @lock: synchronizes accesses to the list of mappings + * + * Note that entries are not periodically evicted from this cache and instead need to be + * explicitly released. This is used primarily for DRM/KMS where the cache's reference is + * released when the last reference to a buffer object represented by a mapping in this + * cache is dropped. */ struct host1x_bo_cache { struct list_head mappings;