Subject: Re: [PATCH 3/6] net: arc_emac: support the phy reset for emac driver

From: Sergei Shtylyov <[email-masked]>
Date: Fri, 11 Mar 2016 21:35:17 +0300

On 03/11/2016 01:55 PM, Caesar Wang wrote:

> This patch adds to support the emac phy reset.
>
> 1) phy-reset-gpios:
> The phy-reset-gpios is an optional property for arc emac device tree boot.
> Change the binding document to match the driver code.

    The binding document is apparently changed in another patch. Not sure what 
you wanted to say here...

> 2) phy-reset-duration:
> Different boards may require different phy reset duration. Add property
> phy-reset-duration for device tree probe, so that the boards that need
> a longer reset duration can specify it in their device tree.
>
> 3) phy-reset-active-high:
> We need that for a custom hardware that needs the reverse reset sequence.

    No, we don't really need that, "phy-reset-gpio" prop can contain this data.

> Of course, this patch will fix the issue on
> https://patchwork.kernel.org/patch/8186801/.
>
> In some cases, the emac couldn't work if you don't have reset the phy.
> Let's add it to happy work.
>
> Signed-off-by: Caesar Wang <[email-masked]>
> ---
>
>   drivers/net/ethernet/arc/emac_main.c | 41 ++++++++++++++++++++++++++++++++++++
>   1 file changed, 41 insertions(+)
>
> diff --git a/drivers/net/ethernet/arc/emac_main.c b/drivers/net/ethernet/arc/emac_main.c
> index 6446af1..42384f6a 100644
> --- a/drivers/net/ethernet/arc/emac_main.c
> +++ b/drivers/net/ethernet/arc/emac_main.c
> @@ -764,6 +764,45 @@ static const struct net_device_ops arc_emac_netdev_ops = {
>   #endif
>   };
>
> +#ifdef CONFIG_OF
> +static void emac_reset_phy(struct net_device *pdev)
> +{
> +	int err, phy_reset;
> +	bool active_high = false;
> +	int msec = 10;
> +	struct device *dev = pdev->dev.parent;
> +	struct device_node *np = dev->of_node;
> +
> +	if (!np)
> +		return;
> +
> +	of_property_read_u32(np, "phy-reset-duration", &msec);
> +	/* A sane reset duration should not be longer than 1s */
> +	if (msec > 1000)
> +		msec = 1;
> +
> +	phy_reset = of_get_named_gpio(np, "phy-reset-gpios", 0);

    Forgot to say that these old integer-base GPIO APIs shouldn't be used by 
the new code, there's new 'struct gpio_desc' based APIs, like devm_gpiod_get() 
etc.

> +	if (!gpio_is_valid(phy_reset))
> +		return;
> +
> +	active_high = of_property_read_bool(np, "phy-reset-active-high");

    Well, I still don't understand why this prop is needed, while the GPIO 
sense is transparently handled by the gpiolib (at least when using DT).

[...]

MBR, Sergei