[realtek] Work around hardware bug on RTL8211B
The RTL8211B seems to have a bug that prevents the link from coming up
unless the MII_MMD_DATA register is cleared.
The Linux kernel driver applies this workaround (in rtl8211b_resume())
only to the specific RTL8211B PHY model, along with a matching
workaround to set bit 9 of MII_MMD_DATA when suspending the PHY.
Since we have no need to ever suspend the PHY, and since writing a
zero ought to be harmless, we just clear the register unconditionally.
Debugged-by: Nikolay Pertsev <nikolay.p@cos.flag.org>
Tested-by: Nikolay Pertsev <nikolay.p@cos.flag.org>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
diff --git a/src/drivers/net/realtek.c b/src/drivers/net/realtek.c
index 0af3416..a43efb6 100644
--- a/src/drivers/net/realtek.c
+++ b/src/drivers/net/realtek.c
@@ -420,6 +420,16 @@
*/
}
+ /* Some cards (e.g. RTL8211B) have a hardware errata that
+ * requires the MII_MMD_DATA register to be cleared before the
+ * link will come up.
+ */
+ if ( ( rc = mii_write ( &rtl->mii, MII_MMD_DATA, 0 ) ) != 0 ) {
+ /* Ignore failures, since the register may not be
+ * present on all PHYs.
+ */
+ }
+
/* Restart autonegotiation */
if ( ( rc = mii_restart ( &rtl->mii ) ) != 0 ) {
DBGC ( rtl, "REALTEK %p could not restart MII: %s\n",
diff --git a/src/include/mii.h b/src/include/mii.h
index e2afef8..515ba22 100644
--- a/src/include/mii.h
+++ b/src/include/mii.h
@@ -23,6 +23,8 @@
#define MII_EXPANSION 0x06 /* Expansion register */
#define MII_CTRL1000 0x09 /* 1000BASE-T control */
#define MII_STAT1000 0x0a /* 1000BASE-T status */
+#define MII_MMD_CTRL 0x0d /* MMD Access Control Register */
+#define MII_MMD_DATA 0x0e /* MMD Access Data Register */
#define MII_ESTATUS 0x0f /* Extended Status */
#define MII_DCOUNTER 0x12 /* Disconnect counter */
#define MII_FCSCOUNTER 0x13 /* False carrier counter */
