stmmac: update the driver version and doc (V4)

Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 1 deletions

diff --git a/Documentation/networking/stmmac.txt b/Documentation/networking/stmmac.txt
index 40ec92ce4c84..8d67980fabe8 100644
--- 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: