[Mesa-dev] egl/android: fence_fd being forced to -1

[Tapani Pälli]

On 06/15/2017 07:57 PM, Rob Clark wrote:
> On Thu, Jun 15, 2017 at 12:04 PM, Tapani Pälli <tapani.palli at intel.com> wrote:
>> On 06/15/2017 06:52 PM, Rob Clark wrote:
>>> On Thu, Jun 15, 2017 at 9:59 AM, Eric Engestrom
>>> <eric.engestrom at imgtec.com> wrote:
>>>> On Thursday, 2017-06-15 13:27:06 +0000, Marathe, Yogesh wrote:
>>>>> Hello,
>>>>>
>>>>> I'm tyring to run flatland native app on android. It apparantly fails
>>>>> because of a fence issue.
>>>>> while debuging further it is observed that droid_window_enqueue_buffer()
>>>>> is forcing
>>>>> fence_fd =-1.
>>> Yogesh, can you describe a bit more what "fails" means?  What sequence
>>> of gl calls, for example, is it making?
>>
>>
>> The problem described shortly: Flatland uses timestamps from Fence objects
>> for calculating time (using getSignalTime API) and in case of having -1 from
>> producer (Mesa) we will end up having same timestamp for startFence and
>> endFence (since both are Fence::NO_FENCE) and thus flatland will keep
>> running forever as it thinks no time has been passed between 2 fences. It is
>> stuck in a loop where it tries to find how many frames are required so that
>> driver will spend certain amount of time doing it.
>>
> hmm, any idea what the getSignalTime() API sits on top of?  I don't
> think we have such a capability with fence fd's..

I don't know much of libsync but it uses libsync functions 
'sync_fence_info' and 'sync_pt_info' to retrieve data from fence fd.

> BR,
> -R


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