ar71xx: add a workaround for ar8316 not always driving the TA bit to low

AR8316 behind a GPIO bitbanged MDIO bus fails to drive the turnaround bit
to low despite returning a valid value. Ignore it and just use the
returned value anyway.

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@28422 3c298f89-4303-0410-b956-a3cf2f4a3e73

diff --git a/target/linux/ar71xx/patches-2.6.39/920-mdio_bitbang_ignore_ta_value.patch b/target/linux/ar71xx/patches-2.6.39/920-mdio_bitbang_ignore_ta_value.patch
new file mode 100644 (file)
index 0000000..39584aa
--- /dev/null
+++ b/target/linux/ar71xx/patches-2.6.39/920-mdio_bitbang_ignore_ta_value.patch
@@ -0,0 +1,20 @@
+--- a/drivers/net/phy/mdio-bitbang.c
++++ b/drivers/net/phy/mdio-bitbang.c
+@@ -165,16 +165,7 @@ static int mdiobb_read(struct mii_bus *b
+ 
+       ctrl->ops->set_mdio_dir(ctrl, 0);
+ 
+-      /* check the turnaround bit: the PHY should be driving it to zero */
+-      if (mdiobb_get_bit(ctrl) != 0) {
+-              /* PHY didn't drive TA low -- flush any bits it
+-               * may be trying to send.
+-               */
+-              for (i = 0; i < 32; i++)
+-                      mdiobb_get_bit(ctrl);
+-
+-              return 0xffff;
+-      }
++      mdiobb_get_bit(ctrl);
+ 
+       ret = mdiobb_get_num(ctrl, 16);
+       mdiobb_get_bit(ctrl);