Re: [PATCH] gpu: host1x: Do not use mapping cache for job submissions

2022-04-06 Thread Thierry Reding 
On Thu, Mar 24, 2022 at 11:30:25AM +0100, Thierry Reding wrote:
> From: Thierry Reding 
> 
> 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 
> ---
>  drivers/gpu/host1x/job.c | 4 ++--
>  include/linux/host1x.h   | 5 +
>  2 files changed, 7 insertions(+), 2 deletions(-)

Applied.

Thierry


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Re: [PATCH] gpu: host1x: Do not use mapping cache for job submissions

2022-04-04 Thread Jon Hunter 



On 24/03/2022 10:30, Thierry Reding wrote:

From: Thierry Reding 

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 



I have tested this and verified that it is working well.

Reviewed-by: Jon Hunter 
Tested-by: Jon Hunter 

Thanks
Jon

--
nvpublic

[PATCH] gpu: host1x: Do not use mapping cache for job submissions

2022-03-24 Thread Thierry Reding 
From: Thierry Reding 

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 
---
 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, >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, 
>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;
-- 
2.35.1