net: phy: Optionally force master mode for RTL PHY
This patch introduces CONFIG_RTL8211X_PHY_FORCE_MASTER. If this
define is set, RTL8211x PHYs (except for the RTL8211F) will have their
1000BASE-T master/slave autonegotiation disabled and forced to master
mode.
This is helpful for PHYs like the RTL8211C which produce unstable links
in slave mode. Such problems have been found on the A20-Olimex-SOM-EVB
and A20-OLinuXino-Lime2.
There is no proper way to identify affected PHYs in software as the
RTL8211C shares its UID with the RTL8211B. Thus, this fix requires
the introduction of an #ifdef.
CC: fradav@gmail.com
CC: merker@debian.org
CC: hdegoede@redhat.com
CC: ijc@hellion.org.uk
CC: joe.hershberger@ni.com
Signed-off-by: Michael Haas <haas@computerlinguist.org>
Tested-by: Karsten Merker <merker@debian.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 2a229b8..e0008fd 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -13,6 +13,27 @@
help
Enable Ethernet PHY (physical media interface) support.
+config RTL8211X_PHY_FORCE_MASTER
+ bool "Ethernet PHY RTL8211x: force 1000BASE-T master mode"
+ depends on PHYLIB
+ help
+ Force master mode for 1000BASE-T on RTl8211x PHYs (except for RTL8211F).
+ This can work around link stability and data corruption issues on gigabit
+ links which can occur in slave mode on certain PHYs, e.g. on the
+ RTL8211C(L).
+
+ Please note that two directly connected devices (i.e. via crossover cable)
+ will not be able to establish a link between each other if they both force
+ master mode. Multiple devices forcing master mode when connected by a
+ network switch do not pose a problem as the switch configures its affected
+ ports into slave mode.
+
+ This option only affects gigabit links. If you must establish a direct
+ connection between two devices which both force master mode, try forcing
+ the link speed to 100MBit/s.
+
+ If unsure, say N.
+
menuconfig NETDEVICES
bool "Network device support"
depends on NET