DMA API trace BASIC USAGE
	===========================


Enable CONFIG_DMA_API_DEBUG
----------------------------
$TOP/kernel/scripts/config \
	--file $OUT/obj/KERNEL/.config \
	-e DMA_API_DEBUG
make -C$TOP/kernel ARCH=arm O=$OUT/obj/KERNEL oldconfig
grep DMA_API_DEBUG $OUT/obj/KERNEL/.config



Via debugfs
-----------
adb shell cat /d/dma-api/dump_{mappings,allocs,allocs_detail}


Via Ftrace
----------
# All ftraces from boot, add "trace_event=dmadebug:*" to kernel command line
sed -i '/strlcpy(cmd_line, boot_command_line, /i \
    \tstrcat(boot_command_line, " trace_event=dmadebug:*");' \
    $TOP/kernel/arch/arm/kernel/setup.c

Or

adb shell "echo 'dmadebug:*' >> /d/tracing/set_event"

adb shell <your_test_here>
adb shell "echo '\!dmadebug:*' >> /d/tracing/set_event"
adb pull /d/tracing/trace

python $TOP/kernel/scripts/tracing/dma-api/trace.py trace