[PATCH 2/2 v2] dma: ipu_idmac: do not lose valid received data in the irq handler

Hi Guennadi,

Hi Detlev

On Mon, 7 Feb 2011, Detlev Zundel wrote:

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Hi Guennadi,

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How small are the frames in you test? What is the highest fps value in
your test?

QVGA, don't know fps exactly, pretty high, between 20 and 60fps, I think. 
Just try different frams sizes, go down to 64x48 or something.

Is this a "real" usage scenario?  It feels that this is not what most
users will do and it certainly is not relevant for our application.  

QVGA at 25 / 50 / 60 fps is _certainly_ very much a real-life scenario.

Yes, sure.  It was the 64x48 pixel you suggested which I believe to be
of doubtful value here.

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Is it possible that if you are interested in such a scenario that you do
the testing?  We have spent quite a lot of time to fix the driver for
real (well full frame) capturing already and I am relucatant to spend
more time for corner cases.  Maybe we should document this as "known
limitations" of the setup?  What do you think?  I'll much rather have a
driver working for real world scenarios than for marginal test cases.

I am interested in avoiding regressions. In principle, this is a DMA 
driver, which I am not maintaining. Dan asked for my ack, so, I tested it 
and found an issue, which I would prefer to have resolved before 
committing. Of course, I don't have a decisive voice in this matter, so, 
the patch can also be merged without my ack. Otherwise - of course you 
don't have to continue testing, I will try to look at the issue as the 
time permits, and Dan will have to decide, whether he is prepared to 
commit this patch in its present form, or he would prefer this issue to be 
clarified.

I'm fully in line with not wanting any regressions.  But is it a
regression if two independent testers report that the patch _improves_
the current situation?  As was shown by Anatolijs log, the current
driver certainly has a bug with respect to the handling of individual
frames.  This buggy behaviour only never showed up because nobody used
the driver on such a granularity.

We certainly appreciate if you can look into your scenario.

Thanks
  Detlev

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