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Message-Id: <200802062208.17435.david-b@pacbell.net>
Date: Wed, 6 Feb 2008 22:08:17 -0800
From: David Brownell <david-b@...bell.net>
To: Claudio Lanconelli <lanconelli.claudio@...ar.com>
Cc: netdev@...r.kernel.org
Subject: Re: [patch 2.6.24-git] net/enc28j60: low power mode
On Wednesday 06 February 2008, Claudio Lanconelli wrote:
> > + for (;;) {
> > + tmp = nolock_regb_read(priv, ESTAT);
> > + if (!(tmp & ESTAT_RXBUSY))
> > + break;
> > + }
> >
> Avoid infinite waiting loops, please.
> Look at enc28j60_phy_read() for example.
Updated patch is appended.
========== CUT HERE
Keep enc28j60 chips in low-power mode when they're not in use.
At typically 120 mA, these chips run hot even when idle; this
low power mode cuts that power usage by a factor of around 100.
This version provides a generic routine to poll a register until
its masked value equals some value ... e.g. bit set or cleared.
It's basically what the previous wait_phy_ready() did, but this
version is generalized to support the handshaking needed to
enter and exit low power mode.
Signed-off-by: David Brownell <dbrownell@...rs.sourceforge.net>
---
drivers/net/enc28j60.c | 70 ++++++++++++++++++++++++++++++++++++++-----------
1 files changed, 55 insertions(+), 15 deletions(-)
--- a/drivers/net/enc28j60.c
+++ b/drivers/net/enc28j60.c
@@ -400,26 +400,31 @@ enc28j60_packet_write(struct enc28j60_ne
mutex_unlock(&priv->lock);
}
-/*
- * Wait until the PHY operation is complete.
- */
-static int wait_phy_ready(struct enc28j60_net *priv)
+static unsigned long msec20_to_jiffies;
+
+static int poll_ready(struct enc28j60_net *priv, u8 reg, u8 mask, u8 val)
{
- unsigned long timeout = jiffies + 20 * HZ / 1000;
- int ret = 1;
+ unsigned long timeout = jiffies + msec20_to_jiffies;
/* 20 msec timeout read */
- while (nolock_regb_read(priv, MISTAT) & MISTAT_BUSY) {
+ while ((nolock_regb_read(priv, reg) & mask) != val) {
if (time_after(jiffies, timeout)) {
if (netif_msg_drv(priv))
- printk(KERN_DEBUG DRV_NAME
- ": PHY ready timeout!\n");
- ret = 0;
- break;
+ dev_dbg(&priv->spi->dev,
+ "reg %02x ready timeout!\n", reg);
+ return -ETIMEDOUT;
}
cpu_relax();
}
- return ret;
+ return 0;
+}
+
+/*
+ * Wait until the PHY operation is complete.
+ */
+static int wait_phy_ready(struct enc28j60_net *priv)
+{
+ return poll_ready(priv, MISTAT, MISTAT_BUSY, 0) ? 0 : 1;
}
/*
@@ -594,6 +599,31 @@ static void nolock_txfifo_init(struct en
nolock_regw_write(priv, ETXNDL, end);
}
+/*
+ * Low power mode shrinks power consumption about 100x, so we'd like
+ * the chip to be in that mode whenever it's inactive.
+ */
+static void enc28j60_lowpower(struct enc28j60_net *priv, bool is_low)
+{
+ if (netif_msg_drv(priv))
+ dev_dbg(&priv->spi->dev, "%s power...\n",
+ is_low ? "low" : "high");
+
+ mutex_lock(&priv->lock);
+ if (is_low) {
+ nolock_reg_bfclr(priv, ECON1, ECON1_RXEN);
+ poll_ready(priv, ESTAT, ESTAT_RXBUSY, 0);
+ poll_ready(priv, ECON1, ECON1_TXRTS, 0);
+ /* ECON2_VRPS was set during initialization */
+ nolock_reg_bfset(priv, ECON2, ECON2_PWRSV);
+ } else {
+ nolock_reg_bfclr(priv, ECON2, ECON2_PWRSV);
+ poll_ready(priv, ESTAT, ESTAT_CLKRDY, ESTAT_CLKRDY);
+ /* caller sets ECON1_RXEN */
+ }
+ mutex_unlock(&priv->lock);
+}
+
static int enc28j60_hw_init(struct enc28j60_net *priv)
{
u8 reg;
@@ -612,8 +642,8 @@ static int enc28j60_hw_init(struct enc28
priv->tx_retry_count = 0;
priv->max_pk_counter = 0;
priv->rxfilter = RXFILTER_NORMAL;
- /* enable address auto increment */
- nolock_regb_write(priv, ECON2, ECON2_AUTOINC);
+ /* enable address auto increment and voltage regulator powersave */
+ nolock_regb_write(priv, ECON2, ECON2_AUTOINC | ECON2_VRPS);
nolock_rxfifo_init(priv, RXSTART_INIT, RXEND_INIT);
nolock_txfifo_init(priv, TXSTART_INIT, TXEND_INIT);
@@ -690,7 +720,9 @@ static int enc28j60_hw_init(struct enc28
static void enc28j60_hw_enable(struct enc28j60_net *priv)
{
- /* enable interrutps */
+ enc28j60_lowpower(priv, false);
+
+ /* enable interrupts */
if (netif_msg_hw(priv))
printk(KERN_DEBUG DRV_NAME ": %s() enabling interrupts.\n",
__FUNCTION__);
@@ -717,6 +749,8 @@ static void enc28j60_hw_disable(struct e
nolock_reg_bfclr(priv, ECON1, ECON1_RXEN);
priv->hw_enable = false;
mutex_unlock(&priv->lock);
+
+ enc28j60_lowpower(priv, true);
}
static int
@@ -734,6 +768,8 @@ enc28j60_setlink(struct net_device *ndev
"hw_reset() failed\n");
ret = -EINVAL;
}
+ enc28j60_lowpower(priv, true);
+
} else {
if (netif_msg_link(priv))
dev_warn(&ndev->dev,
@@ -1537,6 +1573,8 @@ static int __devinit enc28j60_probe(stru
dev->watchdog_timeo = TX_TIMEOUT;
SET_ETHTOOL_OPS(dev, &enc28j60_ethtool_ops);
+ enc28j60_lowpower(priv, true);
+
ret = register_netdev(dev);
if (ret) {
if (netif_msg_probe(priv))
@@ -1582,6 +1620,8 @@ static struct spi_driver enc28j60_driver
static int __init enc28j60_init(void)
{
+ msec20_to_jiffies = msecs_to_jiffies(20);
+
return spi_register_driver(&enc28j60_driver);
}
--
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