On Tue, 21 Oct 2008 19:19:08 +0300
"ext Sakari Ailus" <sakari.ailus@xxxxxxxxx> wrote:
> /* timeout waiting for the controller to respond */
> #define OMAP_I2C_TIMEOUT (msecs_to_jiffies(1000))
> +/* no more busyloop in ns */
> +#define OMAP_I2C_MINOR_TIMEOUT 10
>
> #define OMAP_I2C_REV_REG 0x00
> #define OMAP_I2C_IE_REG 0x04
> @@ -255,6 +257,8 @@ static int omap_i2c_init(struct omap_i2c_dev *dev)
> unsigned long internal_clk = 0;
>
> if (!dev->rev1) {
> + int delay = 0;
> +
> omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, OMAP_I2C_SYSC_SRST);
> /* For some reason we need to set the EN bit before the
> * reset done bit gets set. */
> @@ -262,6 +266,14 @@ static int omap_i2c_init(struct omap_i2c_dev *dev)
> omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
> while (!(omap_i2c_read_reg(dev, OMAP_I2C_SYSS_REG) &
> OMAP_I2C_SYSS_RDONE)) {
> + if (delay < OMAP_I2C_MINOR_TIMEOUT) {
> + ndelay(1);
> + delay++;
> + continue;
> + } else if (delay == OMAP_I2C_MINOR_TIMEOUT) {
> + dev_warn(dev->dev, "minor timeout not enough");
> + delay++;
> + }
> if (time_after(jiffies, timeout)) {
> dev_warn(dev->dev, "timeout waiting "
> "for controller reset\n");
>
I would rather, if there is no need for such a long delay like
OMAP_I2C_TIMEOUT, remove that time_after and msleep(1) stuff and
just loop few iterations with udelay(1). Zero thinked & tested diff
attached.
I would say that ndelay(1) just doesn't look relevant to < 1 GHz
cpus :-)
Jarkko
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -248,16 +248,16 @@ static int omap_i2c_init(struct omap_i2c_dev *dev)
omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, OMAP_I2C_SYSC_SRST);
/* For some reason we need to set the EN bit before the
* reset done bit gets set. */
- timeout = jiffies + OMAP_I2C_TIMEOUT;
+ timeout = 10;
omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
while (!(omap_i2c_read_reg(dev, OMAP_I2C_SYSS_REG) &
OMAP_I2C_SYSS_RDONE)) {
- if (time_after(jiffies, timeout)) {
+ udelay(1);
+ if (--timeout) {
dev_warn(dev->dev, "timeout waiting "
"for controller reset\n");
return -ETIMEDOUT;
}
- msleep(1);
}
}
omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, 0);
