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DMA coherent pool too small

pcduino DMA coherent pool

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#1 dinoduino



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Posted 16 February 2016 - 11:14 AM



On booting pcduino3 Linux 3.4.79+ #5 SMP PREEMPT Wed Oct 15 14:06:46 CST 2014 armv7l armv7l armv7l GNU/Linux


When booting from NAND I have a reliable system, no boot errors.

If i clone NAND to mmc using board-config.sh and then boot from the mmc/SD card I get an error telling me to increase the coherent pool kernel parameter, currently 256KiB


I have added coherent_pool=2048 in uEnv.txt on partition 1 of the SD card but this has no effect.


Can someone please tell me how to fix this?



#2 youkee


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Posted 17 February 2016 - 11:47 AM

How about this?


#3 dinoduino



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Posted 18 February 2016 - 03:03 AM

Thanks youkee but what on this link are you referring to?

Its all Raspberry Pi focussed and nothing I can find names the files to change.


On a pi you can just edit the cmdline in boot to change things, where on the pcduino is the equivalent?

#4 dinoduino



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Posted 22 February 2016 - 04:54 AM

OK I have solved the issue.


If you have booted from SD image you need to mount mmcblk0p1 and edit the uExt.txt file.

I added a line for coherent_pool=2M but that did not work, so i then put that as an argument to setargs and now it appears to be working.

I also changed this in the /boot-mmc/uEnv.txt file so when using board-config to make the SD the pool gets copied across.

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