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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>
This commit is contained in:
Andrew Lunn 2016-08-19 00:01:55 +02:00 committed by David S. Miller
parent 7a7e780cd7
commit 6441e6695a
1 changed files with 6 additions and 9 deletions
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15
drivers/net/dsa/mv88e6xxx/chip.c
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@ -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;