[ 182/218] r8169: RxConfig hack for the 8168evl.

[Greg Kroah-Hartman]

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Francois Romieu <romieu@xxxxxxxxxxxxx>

commit eb2dc35d99028b698cdedba4f5522bc43e576bd2 upstream.

The 8168evl (RTL_GIGA_MAC_VER_34) based Gigabyte GA-990FXA motherboards
are very prone to NETDEV watchdog problems without this change. See
https://bugzilla.kernel.org/show_bug.cgi?id=42899 for instance.

I don't know why it *works*. It's depressingly effective though.

For the record:
- the problem may go along IOMMU (AMD-Vi) errors but it really looks
  like a red herring.
- the patch sets the RX_MULTI_EN bit. If the 8168c doc is any guide,
  the chipset now fetches several Rx descriptors at a time.
- long ago the driver ignored the RX_MULTI_EN bit.
  e542a2269f232d61270ceddd42b73a4348dee2bb changed the RxConfig
  settings. Whatever the problem it's now labeled a regression.
- Realtek's own driver can identify two different 8168evl devices
  (CFG_METHOD_16 and CFG_METHOD_17) where the r8169 driver only
  sees one. It sucks.

Signed-off-by: Francois Romieu <romieu@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>

---
 drivers/net/ethernet/realtek/r8169.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/net/ethernet/realtek/r8169.c
+++ b/drivers/net/ethernet/realtek/r8169.c
@@ -3737,6 +3737,7 @@ static void rtl_init_rxcfg(struct rtl816
 	case RTL_GIGA_MAC_VER_22:
 	case RTL_GIGA_MAC_VER_23:
 	case RTL_GIGA_MAC_VER_24:
+	case RTL_GIGA_MAC_VER_34:
 		RTL_W32(RxConfig, RX128_INT_EN | RX_MULTI_EN | RX_DMA_BURST);
 		break;
 	default:


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