Merge branch 'linux_next' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab...

[pandora-kernel.git] / Documentation / networking / stmmac.txt

diff --git a/Documentation/networking/stmmac.txt b/Documentation/networking/stmmac.txt
index 40ec92c..8d67980 100644 (file)
--- a/Documentation/networking/stmmac.txt
+++ b/Documentation/networking/stmmac.txt
@@ -76,7 +76,16 @@ core.
 
 4.5) DMA descriptors
 Driver handles both normal and enhanced descriptors. The latter has been only
-tested on DWC Ether MAC 10/100/1000 Universal version 3.41a.
+tested on DWC Ether MAC 10/100/1000 Universal version 3.41a and later.
+
+STMMAC supports DMA descriptor to operate both in dual buffer (RING)
+and linked-list(CHAINED) mode. In RING each descriptor points to two
+data buffer pointers whereas in CHAINED mode they point to only one data
+buffer pointer. RING mode is the default.
+
+In CHAINED mode each descriptor will have pointer to next descriptor in
+the list, hence creating the explicit chaining in the descriptor itself,
+whereas such explicit chaining is not possible in RING mode.
 
 4.6) Ethtool support
 Ethtool is supported. Driver statistics and internal errors can be taken using: