netdev - Re: [PATCH RESEND v3 2/3] net: mdio: add reset control for Aspeed MDIO

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Message-Id: <667280e7-526d-4002-9dff-389f6b35ac2f@www.fastmail.com>
Date:   Mon, 11 Apr 2022 09:50:02 +0930
From:   "Andrew Jeffery" <andrew@...id.au>
To:     "Dylan Hung" <dylan_hung@...eedtech.com>,
        "Rob Herring" <robh+dt@...nel.org>,
        "Joel Stanley" <joel@....id.au>, "Andrew Lunn" <andrew@...n.ch>,
        "Heiner Kallweit" <hkallweit1@...il.com>,
        "Russell King" <linux@...linux.org.uk>,
        "David Miller" <davem@...emloft.net>,
        "Jakub Kicinski" <kuba@...nel.org>, pabeni@...hat.com,
        "Philipp Zabel" <p.zabel@...gutronix.de>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        netdev <netdev@...r.kernel.org>
Cc:     BMC-SW@...eedtech.com
Subject: Re: [PATCH RESEND v3 2/3] net: mdio: add reset control for Aspeed MDIO



On Thu, 7 Apr 2022, at 17:27, Dylan Hung wrote:
> Add reset assertion/deassertion for Aspeed MDIO.  There are 4 MDIO
> controllers embedded in Aspeed AST2600 SOC and share one reset control
> register SCU50[3].  To work with old DT blobs which don't have the reset
> property, devm_reset_control_get_optional_shared is used in this change.
>
> Signed-off-by: Dylan Hung <dylan_hung@...eedtech.com>
> Reviewed-by: Philipp Zabel <p.zabel@...gutronix.de>
> ---
>  drivers/net/mdio/mdio-aspeed.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/mdio/mdio-aspeed.c b/drivers/net/mdio/mdio-aspeed.c
> index e2273588c75b..1afb58ccc524 100644
> --- a/drivers/net/mdio/mdio-aspeed.c
> +++ b/drivers/net/mdio/mdio-aspeed.c
> @@ -3,6 +3,7 @@
> 
>  #include <linux/bitfield.h>
>  #include <linux/delay.h>
> +#include <linux/reset.h>
>  #include <linux/iopoll.h>
>  #include <linux/mdio.h>
>  #include <linux/module.h>
> @@ -37,6 +38,7 @@
> 
>  struct aspeed_mdio {
>  	void __iomem *base;
> +	struct reset_control *reset;
>  };
> 
>  static int aspeed_mdio_read(struct mii_bus *bus, int addr, int regnum)
> @@ -120,6 +122,12 @@ static int aspeed_mdio_probe(struct platform_device *pdev)
>  	if (IS_ERR(ctx->base))
>  		return PTR_ERR(ctx->base);
> 
> +	ctx->reset = devm_reset_control_get_optional_shared(&pdev->dev, NULL);
> +	if (IS_ERR(ctx->reset))
> +		return PTR_ERR(ctx->reset);
> +
> +	reset_control_deassert(ctx->reset);
> +
>  	bus->name = DRV_NAME;
>  	snprintf(bus->id, MII_BUS_ID_SIZE, "%s%d", pdev->name, pdev->id);
>  	bus->parent = &pdev->dev;
> @@ -129,6 +137,7 @@ static int aspeed_mdio_probe(struct platform_device *pdev)
>  	rc = of_mdiobus_register(bus, pdev->dev.of_node);
>  	if (rc) {
>  		dev_err(&pdev->dev, "Cannot register MDIO bus!\n");
> +		reset_control_assert(ctx->reset);
>  		return rc;
>  	}
> 
> @@ -139,7 +148,11 @@ static int aspeed_mdio_probe(struct platform_device *pdev)
> 
>  static int aspeed_mdio_remove(struct platform_device *pdev)
>  {
> -	mdiobus_unregister(platform_get_drvdata(pdev));
> +	struct mii_bus *bus = (struct mii_bus *)platform_get_drvdata(pdev);
> +	struct aspeed_mdio *ctx = bus->priv;
> +
> +	reset_control_assert(ctx->reset);

Isn't this unnecessary because you've used the devm_ variant to acquire 
the reset?

Andrew