[Intel-gfx] [PATCH 03/13] staging/android/sync: Move sync framework out of staging

[John Harrison]

On 21/12/2015 10:03, Daniel Vetter wrote:
> On Thu, Dec 17, 2015 at 09:35:03AM -0800, Jesse Barnes wrote:
>> On 12/11/2015 05:11 AM, John.C.Harrison at Intel.com wrote:
>>> From: John Harrison <John.C.Harrison at Intel.com>
>>>
>>> The sync framework is now used by the i915 driver. Therefore it can be
>>> moved out of staging and into the regular tree. Also, the public
>>> interfaces can actually be made public and exported.
>>>
>>> v3: New patch for series.
>>>
>>> Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
>>> Signed-off-by: Geoff Miller <geoff.miller at intel.com>
>>> ---
>>>   drivers/android/Kconfig                |  28 ++
>>>   drivers/android/Makefile               |   2 +
>>>   drivers/android/sw_sync.c              | 260 ++++++++++++
>>>   drivers/android/sw_sync.h              |  59 +++
>>>   drivers/android/sync.c                 | 734 +++++++++++++++++++++++++++++++++
>>>   drivers/android/sync.h                 | 366 ++++++++++++++++
>>>   drivers/android/sync_debug.c           | 256 ++++++++++++
>>>   drivers/android/trace/sync.h           |  82 ++++
>>>   drivers/staging/android/Kconfig        |  28 --
>>>   drivers/staging/android/Makefile       |   2 -
>>>   drivers/staging/android/sw_sync.c      | 260 ------------
>>>   drivers/staging/android/sw_sync.h      |  59 ---
>>>   drivers/staging/android/sync.c         | 734 ---------------------------------
>>>   drivers/staging/android/sync.h         | 366 ----------------
>>>   drivers/staging/android/sync_debug.c   | 256 ------------
>>>   drivers/staging/android/trace/sync.h   |  82 ----
>>>   drivers/staging/android/uapi/sw_sync.h |  32 --
>>>   drivers/staging/android/uapi/sync.h    |  97 -----
>>>   include/uapi/Kbuild                    |   1 +
>>>   include/uapi/sync/Kbuild               |   3 +
>>>   include/uapi/sync/sw_sync.h            |  32 ++
>>>   include/uapi/sync/sync.h               |  97 +++++
>>>   22 files changed, 1920 insertions(+), 1916 deletions(-)
>>>   create mode 100644 drivers/android/sw_sync.c
>>>   create mode 100644 drivers/android/sw_sync.h
>>>   create mode 100644 drivers/android/sync.c
>>>   create mode 100644 drivers/android/sync.h
>>>   create mode 100644 drivers/android/sync_debug.c
>>>   create mode 100644 drivers/android/trace/sync.h
>>>   delete mode 100644 drivers/staging/android/sw_sync.c
>>>   delete mode 100644 drivers/staging/android/sw_sync.h
>>>   delete mode 100644 drivers/staging/android/sync.c
>>>   delete mode 100644 drivers/staging/android/sync.h
>>>   delete mode 100644 drivers/staging/android/sync_debug.c
>>>   delete mode 100644 drivers/staging/android/trace/sync.h
>>>   delete mode 100644 drivers/staging/android/uapi/sw_sync.h
>>>   delete mode 100644 drivers/staging/android/uapi/sync.h
>>>   create mode 100644 include/uapi/sync/Kbuild
>>>   create mode 100644 include/uapi/sync/sw_sync.h
>>>   create mode 100644 include/uapi/sync/sync.h
>>>
>>> diff --git a/drivers/android/Kconfig b/drivers/android/Kconfig
>>> index bdfc6c6..9edcd8f 100644
>>> --- a/drivers/android/Kconfig
>>> +++ b/drivers/android/Kconfig
>>> @@ -32,6 +32,34 @@ config ANDROID_BINDER_IPC_32BIT
>>>   
>>>   	  Note that enabling this will break newer Android user-space.
>>>   
>>> +config SYNC
>>> +	bool "Synchronization framework"
>>> +	default n
>>> +	select ANON_INODES
>>> +	select DMA_SHARED_BUFFER
>>> +	---help---
>>> +	  This option enables the framework for synchronization between multiple
>>> +	  drivers.  Sync implementations can take advantage of hardware
>>> +	  synchronization built into devices like GPUs.
>>> +
>>> +config SW_SYNC
>>> +	bool "Software synchronization objects"
>>> +	default n
>>> +	depends on SYNC
>>> +	---help---
>>> +	  A sync object driver that uses a 32bit counter to coordinate
>>> +	  synchronization.  Useful when there is no hardware primitive backing
>>> +	  the synchronization.
>>> +
>>> +config SW_SYNC_USER
>>> +	bool "Userspace API for SW_SYNC"
>>> +	default n
>>> +	depends on SW_SYNC
>>> +	---help---
>>> +	  Provides a user space API to the sw sync object.
>>> +	  *WARNING* improper use of this can result in deadlocking kernel
>>> +	  drivers from userspace.
>>> +
>>>   endif # if ANDROID
>> IIRC we wanted to drop the user ABI altogether?  I think we can de-stage
>> this even before we push the new ABI on the i915 side to expose the sync
>> points (since we'll need an open source userspace for that), and any
>> changes/cleanups can happen outside of staging.
> Just a head-up: Gustavo Padovan from Collabora is working to de-stage all
> the syncpt stuff. Greg KH merged the TODO update for that work for 4.5,
> which covers consensus (including ack from Google's Greg Hackmann on the
> plan). Given that I think it'd be best to freeload on that effort. But
> that means we need to push all the android/syncpt stuff down in the
> series. I hope that works, and there's no functional depencies in the
> fence conversion/scheduler core?
>
> Thanks, Daniel

Do you have any idea on the timescale for their destaging? Is it 
definitely, definitely happening or still just a 'some point in the 
future it would be nice to...'? The Android driver certainly needs it 
and I believe Jesse's bufferless work will require it too. So sooner is 
greatly preferable to later.

As long as the reset of the fence conversion still goes in then it's not 
all that much effort to extract the sync code. It was all previously 
'#if CONFIG_SYNC' anyway so the system can definitely be made to work 
without it. There are two main patches that add it in, one in the fence 
series and another in the scheduler series. However, if you just drop 
those there might well be a big bunch of merge conflicts to resolve in 
the subsequent patches.

John.