2008-09-07 10:25:02     Alternate modes for PPI-DMA ?? (CPU / burst mode )

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2008-09-07 10:25:02     Alternate modes for PPI-DMA ?? (CPU / burst mode )

renjith kumar (INDIA)

Message: 61756   


hi all,


If this is a stupid question forgive me, but dont forget to reply.


I have a fb0 and fb1 working now with my board with PPI0 and PPI1 respectively.


But my problem is Speed, I use YUV buffers for Both.


When I run only One fb it wokrs fine, but as soon as I open  second application,  it both gets very slow.


JPEGs takes many seconds to load and alter.


Video Goes very slow.I am configuring PPI-DMA as per 7171/7179 driver from the forum.


(Individually OK).


I wonder if theres any alternate method to try instead of this ? (like a CPU mode or any burst mode, something like that), with or without DMA.


please suggest,










2008-09-07 15:15:43     Re: Alternate modes for PPI-DMA ?? (CPU / burst mode )

Mike Frysinger (UNITED STATES)

Message: 61761   


i'm pretty sure there is no such thing.  PPI needs to be constantly feed by DMA, and the bus utilization by two PPI's and Linux is pretty high.


to make sure it isnt a locking/kernel issue, you could try to profile things with JTAG to see where time is being spent.