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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>
This commit is contained in:
Yang Li 2010-11-25 23:29:58 +00:00 committed by David S. Miller
parent b4ff3c90e6
commit d830418e40
1 changed files with 2 additions and 1 deletions
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3
drivers/net/ucc_geth.h
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@ -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 */