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-rw-r--r--Documentation/networking/phy.txt18
1 files changed, 17 insertions, 1 deletions
diff --git a/Documentation/networking/phy.txt b/Documentation/networking/phy.txt
index 3544c98401fd..e839e7efc835 100644
--- a/Documentation/networking/phy.txt
+++ b/Documentation/networking/phy.txt
@@ -272,6 +272,8 @@ Writing a PHY driver
txtsamp: Requests a transmit timestamp at the PHY level for a 'skb'
set_wol: Enable Wake-on-LAN at the PHY level
get_wol: Get the Wake-on-LAN status at the PHY level
+ read_mmd_indirect: Read PHY MMD indirect register
+ write_mmd_indirect: Write PHY MMD indirect register
Of these, only config_aneg and read_status are required to be
assigned by the driver code. The rest are optional. Also, it is
@@ -284,7 +286,21 @@ Writing a PHY driver
Feel free to look at the Marvell, Cicada, and Davicom drivers in
drivers/net/phy/ for examples (the lxt and qsemi drivers have
- not been tested as of this writing)
+ not been tested as of this writing).
+
+ The PHY's MMD register accesses are handled by the PAL framework
+ by default, but can be overridden by a specific PHY driver if
+ required. This could be the case if a PHY was released for
+ manufacturing before the MMD PHY register definitions were
+ standardized by the IEEE. Most modern PHYs will be able to use
+ the generic PAL framework for accessing the PHY's MMD registers.
+ An example of such usage is for Energy Efficient Ethernet support,
+ implemented in the PAL. This support uses the PAL to access MMD
+ registers for EEE query and configuration if the PHY supports
+ the IEEE standard access mechanisms, or can use the PHY's specific
+ access interfaces if overridden by the specific PHY driver. See
+ the Micrel driver in drivers/net/phy/ for an example of how this
+ can be implemented.
Board Fixups