From 58add9fc02e7a9dbab9d80d5fa64f13972e91eb5 Mon Sep 17 00:00:00 2001 From: Steve Glendinning Date: Thu, 26 Mar 2009 07:14:36 +0000 Subject: [PATCH] smsc911x: enforce read-after-write timing restriction on eeprom access The LAN911x datasheet specifies a minimum delay of 45ns between a write of E2P_DATA and any read. This patch adds a single dummy read of BYTE_TEST to enforce this timing constraint. Signed-off-by: Steve Glendinning Signed-off-by: David S. Miller --- drivers/net/smsc911x.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/smsc911x.c b/drivers/net/smsc911x.c index ad3cbc91a8fa..af8f60ca0f57 100644 --- a/drivers/net/smsc911x.c +++ b/drivers/net/smsc911x.c @@ -1680,6 +1680,7 @@ static int smsc911x_eeprom_write_location(struct smsc911x_data *pdata, u8 address, u8 data) { u32 op = E2P_CMD_EPC_CMD_ERASE_ | address; + u32 temp; int ret; SMSC_TRACE(DRV, "address 0x%x, data 0x%x", address, data); @@ -1688,6 +1689,10 @@ static int smsc911x_eeprom_write_location(struct smsc911x_data *pdata, if (!ret) { op = E2P_CMD_EPC_CMD_WRITE_ | address; smsc911x_reg_write(pdata, E2P_DATA, (u32)data); + + /* Workaround for hardware read-after-write restriction */ + temp = smsc911x_reg_read(pdata, BYTE_TEST); + ret = smsc911x_eeprom_send_cmd(pdata, op); } -- 2.20.1