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net: phy: workaround for buggy cable detection by LAN8700 after cable plugging 

* Due to HW bug, LAN8700 sometimes does not detect presence of energy in the
  Ethernet cable in Energy Detect Power-Down mode (e.g while EDPWRDOWN bit is
  set, the ENERGYON bit does not asserted sometimes). This is a common bug of
  LAN87xx family of PHY chips.
* The lan87xx_read_status() was improved to acquire ENERGYON bit. Its previous
  algorythm still not reliable on 100 % and sometimes skip cable plugging.

Signed-off-by: Igor Plyatov <plyatov@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Igor Plyatov 2015-08-14 20:11:02 +03:00 committed by David S. Miller
parent a27cc68b9b
commit 776829de90
1 changed files with 19 additions and 12 deletions
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31
drivers/net/phy/smsc.c
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@ -91,19 +91,18 @@ static int lan911x_config_init(struct phy_device *phydev)
}
/*
* The LAN8710/LAN8720 requires a minimum of 2 link pulses within 64ms of each
* other in order to set the ENERGYON bit and exit EDPD mode. If a link partner
* does send the pulses within this interval, the PHY will remained powered
* down.
*
* This workaround will manually toggle the PHY on/off upon calls to read_status
* in order to generate link test pulses if the link is down. If a link partner
* is present, it will respond to the pulses, which will cause the ENERGYON bit
* to be set and will cause the EDPD mode to be exited.
* The LAN87xx suffers from rare absence of the ENERGYON-bit when Ethernet cable
* plugs in while LAN87xx is in Energy Detect Power-Down mode. This leads to
* unstable detection of plugging in Ethernet cable.
* This workaround disables Energy Detect Power-Down mode and waiting for
* response on link pulses to detect presence of plugged Ethernet cable.
* The Energy Detect Power-Down mode is enabled again in the end of procedure to
* save approximately 220 mW of power if cable is unplugged.
*/
static int lan87xx_read_status(struct phy_device *phydev)
{
int err = genphy_read_status(phydev);
int i;
if (!phydev->link) {
/* Disable EDPD to wake up PHY */
@ -116,8 +115,16 @@ static int lan87xx_read_status(struct phy_device *phydev)
if (rc < 0)
return rc;
/* Sleep 64 ms to allow ~5 link test pulses to be sent */
msleep(64);
/* Wait max 640 ms to detect energy */
for (i = 0; i < 64; i++) {
/* Sleep to allow link test pulses to be sent */
msleep(10);
rc = phy_read(phydev, MII_LAN83C185_CTRL_STATUS);
if (rc < 0)
return rc;
if (rc & MII_LAN83C185_ENERGYON)
break;
};
/* Re-enable EDPD */
rc = phy_read(phydev, MII_LAN83C185_CTRL_STATUS);
@ -191,7 +198,7 @@ static struct phy_driver smsc_phy_driver[] = {
/* basic functions */
.config_aneg = genphy_config_aneg,
.read_status = genphy_read_status,
.read_status = lan87xx_read_status,
.config_init = smsc_phy_config_init,
.soft_reset = smsc_phy_reset,