On 02.05.24 17:17, Ahmad Fatoum wrote:
> The barebox driver currently only ensures that the switch is out of
> reset, but doesn't actually trigger a reset pulse.
>
> The Linux driver, on the other hand, holds reset active for 10ms and
> then waits a whopping 100ms after reset deassertion.
>
> This seems excessive by a thousandfold for at least KSZ9893R[1], whose
> datasheet states:
>
> After the de-assertion of reset, it is recommended to wait a minimum of
> 100µs before starting to program the device through any interface.
>
> Therefore, let's pulse the reset like Linux does and give the switch 100
> microseconds before continuing with the driver probe.
>
> [1]: DS00002420E-page 176
>
> Signed-off-by: Ahmad Fatoum <[email protected]>
I forgot to include the patch prefix, but IMO all three patches are
master material.
Cheers,
Ahmad
> ---
> drivers/net/ksz9477.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ksz9477.c b/drivers/net/ksz9477.c
> index 1abea9d04017..5c5f4ec8d995 100644
> --- a/drivers/net/ksz9477.c
> +++ b/drivers/net/ksz9477.c
> @@ -433,8 +433,10 @@ static int microchip_switch_probe(struct device *dev)
> if (IS_ERR(gpio)) {
> dev_warn(dev, "Failed to get 'reset' GPIO (ignored)\n");
> } else if (gpio) {
> - mdelay(1);
> + gpiod_set_value(gpio, true);
> + mdelay(10);
> gpiod_set_value(gpio, false);
> + udelay(100);
> }
>
> ksz_reset_switch(dev->priv);
--
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