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

[Detlev Zundel <dzu@denx.de>]

Hi Guennadi,

> Hi Detlev
>
> On Mon, 7 Feb 2011, Detlev Zundel wrote:
>
>> Hi Guennadi,
>> 
>> >> 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.

>> 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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