[RFC,PATCHv2,01/12] videobuf2: add cache management members
Commit Message
Extend vb2_buffer and vb2_queue structs with cache management
members.
V4L2 UAPI already contains two buffer flags which user-space,
supposedly, can use to control buffer cache sync:
- V4L2_BUF_FLAG_NO_CACHE_INVALIDATE
- V4L2_BUF_FLAG_NO_CACHE_CLEAN
None of these, however, do anything at the moment. This patch
set is intended to change it.
Since user-space cache management hints are supposed to be
implemented on a per-buffer basis we need to extend vb2_buffer
struct with two new memebers ->need_cache_sync_on_prepare and
->need_cache_sync_on_finish, which will store corresponding
user-space hints.
In order to preserve the existing behaviour, user-space cache
managements flags will be handled only by those drivers that
permit user-space cache hints. That's the purpose of vb2_queue
->allow_cache_hints member. Driver must set ->allow_cache_hints
during queue initialisation to enable cache management hints
mechanism.
Only drivers that set ->allow_cache_hints during queue initialisation
will handle user-space cache management hints. Otherwise hints
will be ignored.
Change-Id: I52beec2a0d021b7a3715b4f6ae4bfd9dc5e94f0d
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
include/media/videobuf2-core.h | 10 ++++++++++
1 file changed, 10 insertions(+)
Comments
On 2/4/20 3:56 AM, Sergey Senozhatsky wrote:
> Extend vb2_buffer and vb2_queue structs with cache management
> members.
>
> V4L2 UAPI already contains two buffer flags which user-space,
> supposedly, can use to control buffer cache sync:
>
> - V4L2_BUF_FLAG_NO_CACHE_INVALIDATE
> - V4L2_BUF_FLAG_NO_CACHE_CLEAN
>
> None of these, however, do anything at the moment. This patch
> set is intended to change it.
>
> Since user-space cache management hints are supposed to be
> implemented on a per-buffer basis we need to extend vb2_buffer
> struct with two new memebers ->need_cache_sync_on_prepare and
> ->need_cache_sync_on_finish, which will store corresponding
> user-space hints.
>
> In order to preserve the existing behaviour, user-space cache
> managements flags will be handled only by those drivers that
> permit user-space cache hints. That's the purpose of vb2_queue
> ->allow_cache_hints member. Driver must set ->allow_cache_hints
> during queue initialisation to enable cache management hints
> mechanism.
>
> Only drivers that set ->allow_cache_hints during queue initialisation
> will handle user-space cache management hints. Otherwise hints
> will be ignored.
>
> Change-Id: I52beec2a0d021b7a3715b4f6ae4bfd9dc5e94f0d
> Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> ---
> include/media/videobuf2-core.h | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index a2b2208b02da..026004180440 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -263,6 +263,10 @@ struct vb2_buffer {
> * after the 'buf_finish' op is called.
> * copied_timestamp: the timestamp of this capture buffer was copied
> * from an output buffer.
> + * need_cache_sync_on_prepare: do not sync/invalidate cache from
> + * buffer's ->prepare() callback.
> + * need_cache_sync_on_finish: do not sync/invalidate cache from buffer's
> + * ->finish() callback.
Shouldn't 'do not' be deleted from the flag descriptions? If the flag is set,
then you need to sync/validate, right?
Regards,
Hans
> * queued_entry: entry on the queued buffers list, which holds
> * all buffers queued from userspace
> * done_entry: entry on the list that stores all buffers ready
> @@ -273,6 +277,8 @@ struct vb2_buffer {
> unsigned int synced:1;
> unsigned int prepared:1;
> unsigned int copied_timestamp:1;
> + unsigned int need_cache_sync_on_prepare:1;
> + unsigned int need_cache_sync_on_finish:1;
>
> struct vb2_plane planes[VB2_MAX_PLANES];
> struct list_head queued_entry;
> @@ -491,6 +497,9 @@ struct vb2_buf_ops {
> * @uses_requests: requests are used for this queue. Set to 1 the first time
> * a request is queued. Set to 0 when the queue is canceled.
> * If this is 1, then you cannot queue buffers directly.
> + * @allow_cache_hints: when set user-space can pass cache management hints in
> + * order to skip cache flush/invalidation on ->prepare() or/and
> + * ->finish().
> * @lock: pointer to a mutex that protects the &struct vb2_queue. The
> * driver can set this to a mutex to let the v4l2 core serialize
> * the queuing ioctls. If the driver wants to handle locking
> @@ -564,6 +573,7 @@ struct vb2_queue {
> unsigned requires_requests:1;
> unsigned uses_qbuf:1;
> unsigned uses_requests:1;
> + unsigned allow_cache_hints:1;
>
> struct mutex *lock;
> void *owner;
>
On (20/02/19 09:05), Hans Verkuil wrote:
> On 2/4/20 3:56 AM, Sergey Senozhatsky wrote:
[..]
> > diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> > index a2b2208b02da..026004180440 100644
> > --- a/include/media/videobuf2-core.h
> > +++ b/include/media/videobuf2-core.h
> > @@ -263,6 +263,10 @@ struct vb2_buffer {
> > * after the 'buf_finish' op is called.
> > * copied_timestamp: the timestamp of this capture buffer was copied
> > * from an output buffer.
> > + * need_cache_sync_on_prepare: do not sync/invalidate cache from
> > + * buffer's ->prepare() callback.
> > + * need_cache_sync_on_finish: do not sync/invalidate cache from buffer's
> > + * ->finish() callback.
>
> Shouldn't 'do not' be deleted from the flag descriptions? If the flag is set,
> then you need to sync/validate, right?
Hmm, kind of work both ways. Maybe the wording can be more specific,
e.g. "Do/skip cache sync/invalidation" even more detailed "When set
perform cache sync/invalidation from ..."
-ss
On 2/19/20 9:16 AM, Sergey Senozhatsky wrote:
> On (20/02/19 09:05), Hans Verkuil wrote:
>> On 2/4/20 3:56 AM, Sergey Senozhatsky wrote:
>
> [..]
>
>>> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
>>> index a2b2208b02da..026004180440 100644
>>> --- a/include/media/videobuf2-core.h
>>> +++ b/include/media/videobuf2-core.h
>>> @@ -263,6 +263,10 @@ struct vb2_buffer {
>>> * after the 'buf_finish' op is called.
>>> * copied_timestamp: the timestamp of this capture buffer was copied
>>> * from an output buffer.
>>> + * need_cache_sync_on_prepare: do not sync/invalidate cache from
>>> + * buffer's ->prepare() callback.
>>> + * need_cache_sync_on_finish: do not sync/invalidate cache from buffer's
>>> + * ->finish() callback.
>>
>> Shouldn't 'do not' be deleted from the flag descriptions? If the flag is set,
>> then you need to sync/validate, right?
>
> Hmm, kind of work both ways. Maybe the wording can be more specific,
> e.g. "Do/skip cache sync/invalidation" even more detailed "When set
> perform cache sync/invalidation from ..."
"When set..." works well. It's explicit.
Regards,
Hans
>
> -ss
>
@@ -263,6 +263,10 @@ struct vb2_buffer {
* after the 'buf_finish' op is called.
* copied_timestamp: the timestamp of this capture buffer was copied
* from an output buffer.
+ * need_cache_sync_on_prepare: do not sync/invalidate cache from
+ * buffer's ->prepare() callback.
+ * need_cache_sync_on_finish: do not sync/invalidate cache from buffer's
+ * ->finish() callback.
* queued_entry: entry on the queued buffers list, which holds
* all buffers queued from userspace
* done_entry: entry on the list that stores all buffers ready
@@ -273,6 +277,8 @@ struct vb2_buffer {
unsigned int synced:1;
unsigned int prepared:1;
unsigned int copied_timestamp:1;
+ unsigned int need_cache_sync_on_prepare:1;
+ unsigned int need_cache_sync_on_finish:1;
struct vb2_plane planes[VB2_MAX_PLANES];
struct list_head queued_entry;
@@ -491,6 +497,9 @@ struct vb2_buf_ops {
* @uses_requests: requests are used for this queue. Set to 1 the first time
* a request is queued. Set to 0 when the queue is canceled.
* If this is 1, then you cannot queue buffers directly.
+ * @allow_cache_hints: when set user-space can pass cache management hints in
+ * order to skip cache flush/invalidation on ->prepare() or/and
+ * ->finish().
* @lock: pointer to a mutex that protects the &struct vb2_queue. The
* driver can set this to a mutex to let the v4l2 core serialize
* the queuing ioctls. If the driver wants to handle locking
@@ -564,6 +573,7 @@ struct vb2_queue {
unsigned requires_requests:1;
unsigned uses_qbuf:1;
unsigned uses_requests:1;
+ unsigned allow_cache_hints:1;
struct mutex *lock;
void *owner;