[PATCH 00/20] ARM: pxa: move core and drivers to dmaengine

Robert Jarzmik robert.jarzmik at free.fr
Fri Aug 9 18:50:15 EDT 2013

Daniel Mack <zonque at gmail.com> writes:

>  * camera driver:
>      I started the transition, but I'm not sure how much sense that
>      makes without access to the hardware. I'd much appreciate if
>      anyone could volunteer for this piece; I'll happily share what
>      I got so far. Sascha, Sachin, Guennadi?
Hi Daniel,

Do you mean this driver ? :

In that case I might help. But before I can do that, I have to be convinced that
dmaengine can deal with this driver. I'm thinking in particular of :
 - "hot running DMA" queuing
 - multiple DMA channel synchronization (ie. 3 channel sync)

All that is described in there :

If someone with dmaengine knowledge could have a look at pxa_camera.txt (maybe
Vinod ?) and tell me that dma_engine framework fullfills the 2 requirements,
then I'll be happy to help.

One minor point though is that I'm working on pxa27x. If the serie is not
compatible in a way with pxa27x, I won't be able to do anything.

Another point I'd like to know, is what is the performance penalty in using
dmaengine, and do you have any figures ?

Lastly, they was debug information to debug descriptors chaining, channel
statuses, requestors. I didn't see where these had gone, could you point me to
the right file ?



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