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Date: Fri, 14 Aug 2015 20:11:02 +0300
From: Igor Plyatov <plyatov@...il.com>
To: linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
f.fainelli@...il.com, joe@...ches.com, luwei.zhou@...escale.com,
richardcochran@...il.com, davem@...emloft.net,
u.kleine-koenig@...gutronix.de, Fabio.Estevam@...escale.com,
LW@...O-electronics.de, Frank.Li@...escale.com, mhei@...mpold.de
Cc: Igor Plyatov <plyatov@...il.com>
Subject: [PATCH v3] 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@...il.com>
---
drivers/net/phy/smsc.c | 31 +++++++++++++++++++------------
1 file changed, 19 insertions(+), 12 deletions(-)
diff --git a/drivers/net/phy/smsc.c b/drivers/net/phy/smsc.c
index c0f6479..d64f016 100644
--- a/drivers/net/phy/smsc.c
+++ b/drivers/net/phy/smsc.c
@@ -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,
--
1.7.9.5
--
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