Thread (6 messages) flat view 6 messages, 3 authors, 2013-08-15
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[PATCH 00/20] ARM: pxa: move core and drivers to dmaengine

From: robert.jarzmik@free.fr (Robert Jarzmik)
Date: 2013-08-09 22:50:15

Daniel Mack [off-list ref] 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 ? :
drivers/media/platform/soc_camera/pxa_camera.c

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 :
  Documentation/video4linux/pxa_camera.txt

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 ?

Cheers.

-- 
Robert
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