[Trac #425] cafe_ccic sporadic oops when running gstreamer

[Zarro Boogs per Child]

#425: cafe_ccic sporadic oops when running gstreamer
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 Reporter:  cjb      |        Owner:  corbet  
     Type:  defect   |       Status:  assigned
 Priority:  blocker  |    Milestone:  BTest-2 
Component:  kernel   |   Resolution:          
 Keywords:           |  
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Comment (by corbet):

 The originally-reported "oops" is actually a memory failure, which is a
 result
 of system memory fragmentation and the fact that the camera controller
 does not
 support scatter/gather I/O.  The driver *must* be able to allocate
 physically-
 contiguous DMA buffers, or the device simply cannot work.  On a system
 where
 physical memory is relatively small, the problem will come about more
 easily.

 I put an option (alloc_bufs_at_load) into the driver with this situation
 in
 mind.  Set that option to 1, and the driver will grab its DMA buffers when
 it
 first initializes - when, hopefully, system memory is relatively pristine
 and
 the allocation is more likely to succeed.  The downside is that the driver
 then
 hogs that memory for the life of the system, regardless of whether the
 camera
 will ever be used.  But, for OLPC use, I believe that option should be
 turned
 on, or you'll see a lot of bug reports like this one.

-- 
Ticket URL: <http://dev.laptop.org/ticket/425#comment:5>
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