Re: ISP CCDC freeze-up on STREAMON

[Michael Jones <michael.jones@matrix-vision.de>]

Hi Laurent,

On 07/20/2011 10:47 AM, Laurent Pinchart wrote:
> 
> Hi Michael,
> 
> Sorry for the late reply.

Likewise :)

> 
> On Thursday 30 June 2011 10:31:52 Michael Jones wrote:
>> Hi Laurent,
>>
>> I'm observing a system freeze-up with the ISP when writing data to memory
>> directly from the ccdc.
>>
>> Here's the sequence I'm using:
>>
>> 0. apply the patch I'm sending separate in this thread.
>>
>> 1. configure the ISP pipeline for the CCDC to deliver V4L2_PIX_FMT_GREY
>> directly from the sensor to memory.
>>
>> 2. yavta -c10 /dev/video2
>>
>> The patch is pretty self-explanatory.  It introduces a loop (with ugly
>> indenting to keep the patch simple) with 100 iterations leaving the device
>> open between them. My system usually hangs up within the first 30
>> iterations.  I've never made it to 100 successfully.  I see the same
>> behavior with user pointers and with mmap, but I don't see it when using
>> data from the previewer.
>>
>> Can you please try this out with your setup?  Even if you can't get 8-bit
>> gray data from your sensor, hopefully you could observe it with any other
>> format directly from the CCDC.
>>
>> I'll postpone further discussion until you confirm that you can reproduce
>> the behavior.  As the patch illustrates, it looks like it is hanging up in
>> STREAMON.
> 
> I've tested this with a serial CSI-2 sensor and a parallel sensor (MT9V032, in 
> both 8-bit and 10-bit modes, albeit with SGRBG8 instead of GREY for the 8-bit 
> mode), and I can't reproduce the issue.
> 
> I thought I've asked you already but can't find this in my mailbox, so I 
> apologize if I have, but could you try increasing vertical blanking and see if 
> it helps ?
> 

I think that was the first time you suggested that. Indeed, if I stretch
out the time between frames, the problem goes away. I haven't tested it
precisely to see how long it needs to be to work correctly. But what
does this tell me? This isn't a very appealing fix as 1) I would have to
fish around for a minimum vertical blank time that works and 2) this
would slow down the frame rate for the normal case, when frames are just
being streamed uninterrupted.

-Michael

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