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

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Message-ID: <ZFtwU1svXhZ/xrnJ@corigine.com>
Date:   Wed, 10 May 2023 12:22:11 +0200
From:   Simon Horman <simon.horman@...igine.com>
To:     Yan Wang <rk.code@...look.com>
Cc:     andrew@...n.ch, hkallweit1@...il.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux@...linux.org.uk
Subject: Re: [PATCH v3] net: mdiobus: Add a function to deassert reset

On Wed, May 10, 2023 at 04:15:22PM +0800, Yan Wang wrote:
> It is possible to mount multiple sub-devices on the mido bus.
> The hardware power-on does not necessarily reset these devices.
> The device may be in an uncertain state, causing the device's ID
> to not be scanned.
> 
> So, before adding a reset to the scan, make sure the device is in
> normal working mode.
> 
> I found that the subsequent drive registers the reset pin into the
> structure of the sub-device to prevent conflicts, so release the
> reset pin.
> 
> Signed-off-by: Yan Wang <rk.code@...look.com>
> ---
> v3:
>   - fixed commit message
> v2: https://lore.kernel.org/all/KL1PR01MB54482416A8BE0D80EA27223CE6779@KL1PR01MB5448.apcprd01.prod.exchangelabs.com/
>   - fixed commit message
>   - Using gpiod_ replace gpio_
> v1: https://lore.kernel.org/all/KL1PR01MB5448631F2D6F71021602117FE6769@KL1PR01MB5448.apcprd01.prod.exchangelabs.com/
>   - Incorrect description of commit message.
>   - The gpio-api too old
> ---
>  drivers/net/mdio/fwnode_mdio.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)
> 
> diff --git a/drivers/net/mdio/fwnode_mdio.c b/drivers/net/mdio/fwnode_mdio.c
> index 1183ef5e203e..6695848b8ef2 100644
> --- a/drivers/net/mdio/fwnode_mdio.c
> +++ b/drivers/net/mdio/fwnode_mdio.c
> @@ -57,6 +57,20 @@ fwnode_find_mii_timestamper(struct fwnode_handle *fwnode)
>  	return register_mii_timestamper(arg.np, arg.args[0]);
>  }
>  
> +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);

Hi Yan,

As this calls fwnode_gpiod_get_index()
do you need to include linux/gpio/consumer.h ?

> +	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);
> +}
> +

...