Re: [PATCH v3] net: mdiobus: Add a function to deassert reset

[Yan Wang]

On 5/11/2023 6:15 AM, Andrew Lunn wrote:
> > +static void fwnode_mdiobus_pre_enable_phy(struct fwnode_handle *fwnode)
> > +{
> > +	struct gpio_desc *reset;
> > +
> > +	reset = fwnode_gpiod_get_index(fwnode, "reset", 0, GPIOD_OUT_HIGH, NULL);
> > +	if (IS_ERR(reset) && PTR_ERR(reset) != -EPROBE_DEFER)
> > +		return;
> > +
> > +	usleep_range(100, 200);
> > +	gpiod_set_value_cansleep(reset, 0);
> > +	/*Release the reset pin,it needs to be registered with the PHY.*/
> > +	gpiod_put(reset);
> You are still putting it into reset, and then taking it out of
> reset. This is what i said should not be done. Please only take it out
> of reset if it is in reset.
>
> Also, you ignored my comments about delay after reset.
>
> Documentation/devicetree/bindings/net/ethernet-phy.yaml says:
>
>    reset-gpios:
>      maxItems: 1
>      description:
>        The GPIO phandle and specifier for the PHY reset signal.
>
>    reset-assert-us:
>      description:
>        Delay after the reset was asserted in microseconds. If this
>        property is missing the delay will be skipped.
>
>    reset-deassert-us:
>      description:
>        Delay after the reset was deasserted in microseconds. If
>        this property is missing the delay will be skipped.
>
> You are deasserting the reset, so you should look for this property,
> and if it is there, delay for that amount. Some PHYs take a while
> before they will respond on the bus.
I'm very sorry, I forgot. Thank you
>         Andrew