From 242bcd5ba1dcea802c0ad03344f626a727212399 Mon Sep 17 00:00:00 2001 From: Alexander Kochetkov Date: Thu, 13 Nov 2014 05:26:19 +0400 Subject: [PATCH] net/smsc911x: Fix rare soft reset timeout issue due to PHY power-down mode The patch affect SMSC LAN generation 4 chips with integrated PHY (LAN9221). It is possible that PHY could enter power-down mode (ENERGYON clear), between ENERGYON bit check in smsc911x_phy_disable_energy_detect and SRST bit set in smsc911x_soft_reset. This could happen, for example, if someone disconnect ethernet cable between the checks. The PHY in a power-down mode would prevent the MAC portion of chip to be software reseted. Initially found by code review, confirmed later using test case. This is low probability issue, and in order to reproduce it you have to run the script: while true; do ifconfig eth0 down ifconfig eth0 up || break done While the script is running you have to plug/unplug ethernet cable many times (using gpio controlled ethernet switch, for example) until get: [ 4516.477783] ADDRCONF(NETDEV_UP): eth0: link is not ready [ 4516.512207] smsc911x smsc911x.0: eth0: SMSC911x/921x identified at 0xce006000, IRQ: 336 [ 4516.524658] ADDRCONF(NETDEV_UP): eth0: link is not ready [ 4516.559082] smsc911x smsc911x.0: eth0: SMSC911x/921x identified at 0xce006000, IRQ: 336 [ 4516.571990] ADDRCONF(NETDEV_UP): eth0: link is not ready ifconfig: SIOCSIFFLAGS: Input/output error The patch was reviewed by Steve Glendinning and Microchip Team. Signed-off-by: Alexander Kochetkov Acked-by: Steve Glendinning Signed-off-by: David S. Miller --- drivers/net/ethernet/smsc/smsc911x.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c index affb29da353e..1e1f6194cb37 100644 --- a/drivers/net/ethernet/smsc/smsc911x.c +++ b/drivers/net/ethernet/smsc/smsc911x.c @@ -1356,12 +1356,8 @@ static int smsc911x_phy_disable_energy_detect(struct smsc911x_data *pdata) return rc; } - /* - * If energy is detected the PHY is already awake so is not necessary - * to disable the energy detect power-down mode. - */ - if ((rc & MII_LAN83C185_EDPWRDOWN) && - !(rc & MII_LAN83C185_ENERGYON)) { + /* Only disable if energy detect mode is already enabled */ + if (rc & MII_LAN83C185_EDPWRDOWN) { /* Disable energy detect mode for this SMSC Transceivers */ rc = phy_write(pdata->phy_dev, MII_LAN83C185_CTRL_STATUS, rc & (~MII_LAN83C185_EDPWRDOWN)); -- 2.20.1