dsa: mv88e6xxx: Timeout based on iterations, not time

The mv88e6xxx driver times out operations on the switch based on
looping until an elapsed wall clock time is reached. However, if
usleep_range() sleeps much longer than expected, it could timeout with
an error without actually checking to see if the devices has completed
the operation. So replace the elapsed time with a fixed upper bound on
the number of loops.

Testing on various switches has shown that switches takes either 0 or
1 iteration, so a maximum of 16 iterations is a safe limit.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index a230fcba5b641368c67cfc82e5992498d5343652..ac8e9af4879f2b63dd26081c73cec4a99baad223 100644 (file)
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -309,9 +309,9 @@ static int mv88e6xxx_serdes_write(struct mv88e6xxx_chip *chip, int reg, u16 val)
 static int mv88e6xxx_wait(struct mv88e6xxx_chip *chip, int addr, int reg,
                          u16 mask)
 {
-       unsigned long timeout = jiffies + HZ / 10;
+       int i;
 
-       while (time_before(jiffies, timeout)) {
+       for (i = 0; i < 16; i++) {
                u16 val;
                int err;
 
@@ -375,7 +375,7 @@ static int _mv88e6xxx_reg_write(struct mv88e6xxx_chip *chip, int addr,
 static int mv88e6xxx_ppu_disable(struct mv88e6xxx_chip *chip)
 {
        int ret;
-       unsigned long timeout;
+       int i;
 
        ret = _mv88e6xxx_reg_read(chip, REG_GLOBAL, GLOBAL_CONTROL);
        if (ret < 0)
@@ -386,8 +386,7 @@ static int mv88e6xxx_ppu_disable(struct mv88e6xxx_chip *chip)
        if (ret)
                return ret;
 
-       timeout = jiffies + 1 * HZ;
-       while (time_before(jiffies, timeout)) {
+       for (i = 0; i < 16; i++) {
                ret = _mv88e6xxx_reg_read(chip, REG_GLOBAL, GLOBAL_STATUS);
                if (ret < 0)
                        return ret;
@@ -403,8 +402,7 @@ static int mv88e6xxx_ppu_disable(struct mv88e6xxx_chip *chip)
 
 static int mv88e6xxx_ppu_enable(struct mv88e6xxx_chip *chip)
 {
-       int ret, err;
-       unsigned long timeout;
+       int ret, err, i;
 
        ret = _mv88e6xxx_reg_read(chip, REG_GLOBAL, GLOBAL_CONTROL);
        if (ret < 0)
@@ -415,8 +413,7 @@ static int mv88e6xxx_ppu_enable(struct mv88e6xxx_chip *chip)
        if (err)
                return err;
 
-       timeout = jiffies + 1 * HZ;
-       while (time_before(jiffies, timeout)) {
+       for (i = 0; i < 16; i++) {
                ret = _mv88e6xxx_reg_read(chip, REG_GLOBAL, GLOBAL_STATUS);
                if (ret < 0)
                        return ret;