[PATCH 2/2] netdev/fec: fix performance impact from mdio poll operation
Bryan Wu
bryan.wu at canonical.com
Thu Apr 8 06:44:59 UTC 2010
BugLink: http://bugs.launchpad.net/bugs/546649
BugLink: http://bugs.launchpad.net/bugs/457878
After introducing phylib supporting, users experienced performace drop. That is
because of the mdio polling operation of phylib. Use msleep to replace the busy
waiting cpu_relax() and remove the warning message.
Signed-off-by: Bryan Wu <bryan.wu at canonical.com>
---
drivers/net/fec.c | 45 +++++++++++++++++++++------------------------
1 files changed, 21 insertions(+), 24 deletions(-)
diff --git a/drivers/net/fec.c b/drivers/net/fec.c
index 53240d3..2280373 100644
--- a/drivers/net/fec.c
+++ b/drivers/net/fec.c
@@ -216,7 +216,7 @@ static void fec_stop(struct net_device *dev);
#define FEC_MMFR_TA (2 << 16)
#define FEC_MMFR_DATA(v) (v & 0xffff)
-#define FEC_MII_TIMEOUT 10000
+#define FEC_MII_TIMEOUT 10
/* Transmitter timeout */
#define TX_TIMEOUT (2 * HZ)
@@ -624,13 +624,29 @@ spin_unlock:
/*
* NOTE: a MII transaction is during around 25 us, so polling it...
*/
-static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
+static int fec_enet_mdio_poll(struct fec_enet_private *fep)
{
- struct fec_enet_private *fep = bus->priv;
int timeout = FEC_MII_TIMEOUT;
fep->mii_timeout = 0;
+ /* wait for end of transfer */
+ while (!(readl(fep->hwp + FEC_IEVENT) & FEC_ENET_MII)) {
+ msleep(1);
+ if (timeout-- < 0) {
+ fep->mii_timeout = 1;
+ break;
+ }
+ }
+
+ return 0;
+}
+
+static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
+{
+ struct fec_enet_private *fep = bus->priv;
+
+
/* clear MII end of transfer bit*/
writel(FEC_ENET_MII, fep->hwp + FEC_IEVENT);
@@ -639,15 +655,7 @@ static int fec_enet_mdio_read(struct mii_bus *bus, int mii_id, int regnum)
FEC_MMFR_PA(mii_id) | FEC_MMFR_RA(regnum) |
FEC_MMFR_TA, fep->hwp + FEC_MII_DATA);
- /* wait for end of transfer */
- while (!(readl(fep->hwp + FEC_IEVENT) & FEC_ENET_MII)) {
- cpu_relax();
- if (timeout-- < 0) {
- fep->mii_timeout = 1;
- printk(KERN_ERR "FEC: MDIO read timeout\n");
- return -ETIMEDOUT;
- }
- }
+ fec_enet_mdio_poll(fep);
/* return value */
return FEC_MMFR_DATA(readl(fep->hwp + FEC_MII_DATA));
@@ -657,9 +665,6 @@ static int fec_enet_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
u16 value)
{
struct fec_enet_private *fep = bus->priv;
- int timeout = FEC_MII_TIMEOUT;
-
- fep->mii_timeout = 0;
/* clear MII end of transfer bit*/
writel(FEC_ENET_MII, fep->hwp + FEC_IEVENT);
@@ -670,15 +675,7 @@ static int fec_enet_mdio_write(struct mii_bus *bus, int mii_id, int regnum,
FEC_MMFR_TA | FEC_MMFR_DATA(value),
fep->hwp + FEC_MII_DATA);
- /* wait for end of transfer */
- while (!(readl(fep->hwp + FEC_IEVENT) & FEC_ENET_MII)) {
- cpu_relax();
- if (timeout-- < 0) {
- fep->mii_timeout = 1;
- printk(KERN_ERR "FEC: MDIO write timeout\n");
- return -ETIMEDOUT;
- }
- }
+ fec_enet_mdio_poll(fep);
return 0;
}
--
1.7.0.1
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