[PATCH v2 1/2] i2c: piix4: Use usleep_range()

Guenter Roeck
2018-02-26T20:46:52Z

The piix4 i2c driver is extremely slow. Replacing msleep()
with usleep_range() increases its speed substantially.
Use sleep ranges similar to those used in the i2c-801 driver
to keep things simple.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v2: Changed timeout values for usleep_range()
2000/2000 -> 2000/2100
500/1000 -> 250/500
200/500 -> 250/500

drivers/i2c/busses/i2c-piix4.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 462948e2c535..4c1f6aaec0fc 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -462,13 +462,13 @@ static int piix4_transaction(struct i2c_adapter *piix4_adapter)

/* We will always wait for a fraction of a second! (See PIIX4 docs errata) */
if (srvrworks_csb5_delay) /* Extra delay for SERVERWORKS_CSB5 */
- msleep(2);
+ usleep_range(2000, 2100);
else
- msleep(1);
+ usleep_range(250, 500);

while ((++timeout < MAX_TIMEOUT) &&
((temp = inb_p(SMBHSTSTS)) & 0x01))
- msleep(1);
+ usleep_range(250, 500);

/* If the SMBus is still busy, we give up */
if (timeout == MAX_TIMEOUT) {
--
2.7.4