AM572x BUS error while reading from DCE buffers

Shridhar Majali

Prodigy 140 points

Other Parts Discussed in Thread: AM5728

Hi,

We have integrated the video encoder on AM5728 platform. We are using Processor-SDK 02.00.00.

The integrated encoder is working properly. We notice once issue while running encoder.

In application encoder output buffer is used by 2 different threads to read the data.

Occasionally we observe BUS error, and it is random.

If one of the thread reading the encoder output buffer is disabled this issue is not noticed,

The input and output buffers of the encoder are allocated using omap_bo_new() with OMAP_BO_WC flag enabled.

Please let us know how this issue can be resolved.

Thanks in advance.

Regards,

Shridhar

over 9 years ago

0 Biser Gatchev-XID over 9 years ago

TI__Guru**** 393215 points

Hi,

I will forward this to the software team.

0 Biser Gatchev-XID over 9 years ago in reply to Biser Gatchev-XID

TI__Guru**** 393215 points

Please post which SDK is this - Linux or RTOS?

0 Shridhar Majali over 9 years ago in reply to Biser Gatchev-XID

Prodigy 140 points

Hi Biser,

This is Linux.

Regards,
Shridhar

0 Manisha Agrawal over 9 years ago in reply to Shridhar Majali

TI__Mastermind 22946 points

Are you using gstreamer framework?

0 Pooja Prajod over 9 years ago in reply to Manisha Agrawal

TI__Prodigy 745 points

Hi,

Please confirm if you are using the gstreamer framework. Also please share the error logs.

Thanks and Regards,

Pooja Prajod

0 Shridhar Majali over 9 years ago in reply to Manisha Agrawal

Prodigy 140 points

Hi,

We are not using gstreamer framework. We are using our own media framework and we have integrated the encoder using VIDENC2 interface.

Regards,
Shridhar

0 Shridhar Majali over 9 years ago in reply to Shridhar Majali

Prodigy 140 points

Hi,

We do not get any errors, the crash is observed randomly during memcpy().
So there are two threads which access the encoder ouptut DCE buffers and copy the encoded data to 2 different buffers allocated from heap.

Regards,
Shridhar

0 Pooja Prajod over 9 years ago in reply to Shridhar Majali

TI__Prodigy 745 points

Hi,
1. The crash occurs randomly and is not 100% reproducible
2. The crash is not observed with single thread

From the above statements, I feel this has something to do with simultaneous access (which is ok for a read scenario). Is there a lock in place before memcpy of buffer? As far as I know memcpy is not thread-safe

Thanks and Regards,
Pooja Prajod

0 Shridhar Majali over 9 years ago in reply to Pooja Prajod

Prodigy 140 points

Hi,

Thank you for the information. We will try using the locks before performing memcpy().

Regards,
Shridhar

0 Manu Iyengar over 8 years ago in reply to Pooja Prajod

Intellectual 590 points

Hi,

I'm facing a very similar issue resulting in bus error. I'm trying to use video encoder in slice mode (videnc2Params.outputDataMode = IVIDEO_SLICEMODE). Here, both codec and application access DCE allocated buffers simultaneously. However, application only reads data from the DCE buffers.

Pooja Prajod said:

From the above statements, I feel this has something to do with simultaneous access (which is ok for a read scenario). Is there a lock in place before memcpy of buffer? As far as I know memcpy is not thread-safe

Does this mean simultaneous access of DCE buffers (1 write, multiple read) is permitted? If so, how can this bus error be avoided?

System details -

Processor: AM5728

SDK: PSDK 02.00.00

Regards,

Manu

0 Ramprasad over 8 years ago in reply to Manu Iyengar

TI__Mastermind 30480 points

Hi Manu,

What is the kernel version in the SDK?
the below patch should resolve the Bus Error issue
lists.freedesktop.org/.../047624.html

-EBUSY error was not handled here earlier.

Ram

0 Pooja Prajod over 8 years ago in reply to Manu Iyengar

TI__Prodigy 745 points

Hi,

The constraint is on lock. Is the application locking the buffer?? I will check with codec team if there is anything specific about slice mode.

Regards,

Pooja Prajod

0 Manu Iyengar over 8 years ago in reply to Ramprasad

Intellectual 590 points

Hello Ram,

Thanks for the solution! This seems to have fixed the bus error issue I was facing.

FYI, the kernel version i'm using is 4.1.6

Pooja Prajod said:

The constraint is on lock. Is the application locking the buffer?? I will check with codec team if there is anything specific about slice mode.

Thanks for the suggestion. The application is not locking the buffer. I hope this won't result in any other issues.

Regards,

Manu

0 Ramprasad over 8 years ago in reply to Manu Iyengar

TI__Mastermind 30480 points

Hi Manu,
If Encoder is configured to generate B frames , then explict dce_buf_lock/unlock should be done on encoder input buffers/freeBufID in the application.
IVIDEO_SLICEMODE means B frames can not exist, so explict locking/unlocking is not required.

0 Manu Iyengar over 8 years ago in reply to Ramprasad

Intellectual 590 points

Hi Ram,

Ramprasad said:

If Encoder is configured to generate B frames , then explict dce_buf_lock/unlock should be done on encoder input buffers/freeBufID in the application.
IVIDEO_SLICEMODE means B frames can not exist, so explict locking/unlocking is not required.

Great! Thanks again for confirming this

Regards,

Manu

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AM572x BUS error while reading from DCE buffers