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authorArnd Bergmann <arnd@arndb.de>2009-06-12 09:53:47 +0200
committerArnd Bergmann <arnd@arndb.de>2009-06-12 11:32:58 +0200
commit5b02ee3d219f9e01b6e9146e25613822cfc2e5ce (patch)
tree7ce9126738c3cf4b37d67170d0e4b34818c057a9 /Documentation/DMA-API.txt
parent26a28fa4fea5b8c65713aa50c124f76a88c7924d (diff)
parent8ebf975608aaebd7feb33d77f07ba21a6380e086 (diff)
downloadop-kernel-dev-5b02ee3d219f9e01b6e9146e25613822cfc2e5ce.zip
op-kernel-dev-5b02ee3d219f9e01b6e9146e25613822cfc2e5ce.tar.gz
asm-generic: merge branch 'master' of torvalds/linux-2.6
Fixes a merge conflict against the x86 tree caused by a fix to atomic.h which I renamed to atomic_long.h. Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'Documentation/DMA-API.txt')
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diff --git a/Documentation/DMA-API.txt b/Documentation/DMA-API.txt
index d9aa43d..25fb8bc 100644
--- a/Documentation/DMA-API.txt
+++ b/Documentation/DMA-API.txt
@@ -704,12 +704,24 @@ this directory the following files can currently be found:
The current number of free dma_debug_entries
in the allocator.
+ dma-api/driver-filter
+ You can write a name of a driver into this file
+ to limit the debug output to requests from that
+ particular driver. Write an empty string to
+ that file to disable the filter and see
+ all errors again.
+
If you have this code compiled into your kernel it will be enabled by default.
If you want to boot without the bookkeeping anyway you can provide
'dma_debug=off' as a boot parameter. This will disable DMA-API debugging.
Notice that you can not enable it again at runtime. You have to reboot to do
so.
+If you want to see debug messages only for a special device driver you can
+specify the dma_debug_driver=<drivername> parameter. This will enable the
+driver filter at boot time. The debug code will only print errors for that
+driver afterwards. This filter can be disabled or changed later using debugfs.
+
When the code disables itself at runtime this is most likely because it ran
out of dma_debug_entries. These entries are preallocated at boot. The number
of preallocated entries is defined per architecture. If it is too low for you
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