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

Jean Delvare
2018-03-01T11:04:04Z

On Mon, 26 Feb 2018 12:46:52 -0800, Guenter Roeck wrote:
> 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) {

Reviewed-by: Jean Delvare <jdelvare@suse.de>

--
Jean Delvare
SUSE L3 Support