From d830418e4085d65b3f8bad3216a37bc986ecd17d Mon Sep 17 00:00:00 2001
From: Yang Li <leoli@freescale.com>
Date: Thu, 25 Nov 2010 23:29:58 +0000
Subject: [PATCH] ucc_geth: fix ucc halt problem in half duplex mode
In commit 58933c64(ucc_geth: Fix the wrong the Rx/Tx FIFO size),
the UCC_GETH_UTFTT_INIT is set to 512 based on the recommendation
of the QE Reference Manual. But that will sometimes cause tx halt
while working in half duplex mode.
According to errata draft QE_GENERAL-A003(High Tx Virtual FIFO
threshold size can cause UCC to halt), setting UTFTT less than
[(UTFS x (M - 8)/M) - 128] will prevent this from happening
(M is the minimum buffer size).
The patch changes UTFTT back to 256.
Signed-off-by: Li Yang <leoli@freescale.com>
Cc: Jean-Denis Boyer <jdboyer@media5corp.com>
Cc: Andreas Schmitz <Andreas.Schmitz@riedel.net>
Cc: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
drivers/net/ucc_geth.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ucc_geth.h b/drivers/net/ucc_geth.h
index 05a95586f3c5..055b87ab4f07 100644
--- a/drivers/net/ucc_geth.h
+++ b/drivers/net/ucc_geth.h
@@ -899,7 +899,8 @@ struct ucc_geth_hardware_statistics {
#define UCC_GETH_UTFS_INIT 512 /* Tx virtual FIFO size
*/
#define UCC_GETH_UTFET_INIT 256 /* 1/2 utfs */
-#define UCC_GETH_UTFTT_INIT 512
+#define UCC_GETH_UTFTT_INIT 256 /* 1/2 utfs
+ due to errata */
/* Gigabit Ethernet (1000 Mbps) */
#define UCC_GETH_URFS_GIGA_INIT 4096/*2048*/ /* Rx virtual
FIFO size */
--
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