On Fri, Jan 27, 2023 at 05:56:43AM +1100, John Watts wrote:
> udelay isn't provided in the PBL, so use our own definition.
>
> This avoids boards having to define udelay in their code.
>
> Signed-off-by: John Watts <contact@xxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-imx-early.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-imx-early.c b/drivers/i2c/busses/i2c-imx-early.c
> index 6c8bdc7904..fcf279eff8 100644
> --- a/drivers/i2c/busses/i2c-imx-early.c
> +++ b/drivers/i2c/busses/i2c-imx-early.c
> @@ -90,6 +90,13 @@ static int i2c_fsl_acked(struct fsl_i2c *fsl_i2c)
> return i2c_fsl_poll_status(fsl_i2c, 0, I2SR_RXAK);
> }
>
> +static void __udelay(int us)
> +{
> + volatile int i;
> +
> + for (i = 0; i < us * 1000; i++);
> +}
This takes around 5 times too long on a i.MX8MM and around 50 times too
long on a i.MX6Q. This was measured under a regular barebox on the
shell. In an early environment with MMU disabled it takes 730 times too
long.
Maybe we could do this:
static void __udelay(void *base, int us)
{
int i;
for (i = 0; i < us * 4; i++)
readb(base);
}
The time spent for a register read depends on the bus clock which
doesn't change that much between the different SoCs.
Sascha
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