Re: [PATCH v4 2/2] hwrng: bcm2835: add reset support

From: Philipp Zabel <p.zabel@pengutronix.de>
To: "Álvaro Fernández Rojas" <noltari@gmail.com>,
	"Matt Mackall" <mpm@selenic.com>,
	"Herbert Xu" <herbert@gondor.apana.org.au>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Nicolas Saenz Julienne" <nsaenzjulienne@suse.de>,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"Ray Jui" <rjui@broadcom.com>,
	"Scott Branden" <sbranden@broadcom.com>,
	bcm-kernel-feedback-list@broadcom.com,
	"Mark Brown" <broonie@kernel.org>,
	"Guenter Roeck" <linux@roeck-us.net>,
	"Bjorn Andersson" <bjorn.andersson@linaro.org>,
	"Nícolas F. R. A. Prado" <nfraprado@protonmail.com>,
	"Rikard Falkeborn" <rikard.falkeborn@gmail.com>,
	"Stefan Wahren" <stefan.wahren@i2se.com>,
	linux-crypto@vger.kernel.org, devicetree@vger.kernel.org,
	linux-rpi-kernel@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 2/2] hwrng: bcm2835: add reset support
Date: Wed, 03 Mar 2021 14:52:17 +0100	[thread overview]
Message-ID: <cb7e29012e15ff10916374f911c74430fc3f5b32.camel@pengutronix.de> (raw)
In-Reply-To: <20210224082230.29015-3-noltari@gmail.com>

Hi Álvaro,

On Wed, 2021-02-24 at 09:22 +0100, Álvaro Fernández Rojas wrote:
[...]
> @@ -115,6 +121,8 @@ static void bcm2835_rng_cleanup(struct hwrng *rng)
>  	/* disable rng hardware */
>  	rng_writel(priv, 0, RNG_CTRL);
>  
> +	reset_control_rearm(priv->reset);
> +
>  	if (!IS_ERR(priv->clk))
>  		clk_disable_unprepare(priv->clk);
>  }
> @@ -159,6 +167,10 @@ static int bcm2835_rng_probe(struct platform_device *pdev)
>  	if (PTR_ERR(priv->clk) == -EPROBE_DEFER)
>  		return -EPROBE_DEFER;
>  
> +	priv->reset = devm_reset_control_get_optional_exclusive(dev, NULL);
> +	if (IS_ERR(priv->reset))
> +		return PTR_ERR(priv->reset);
> +
>  	priv->rng.name = pdev->name;
>  	priv->rng.init = bcm2835_rng_init;
>  	priv->rng.read = bcm2835_rng_read;

That doesn't seem right. reset_control_rearm() doesn't do anything if
the reset control is exclusive. Either the reset control should be
requested as shared, or the _rearm should be removed.

regards
Philipp