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

From: Florian Fainelli <f.fainelli@gmail.com>
To: "Álvaro Fernández Rojas" <noltari@gmail.com>,
	"Philipp Zabel" <p.zabel@pengutronix.de>
Cc: "Matt Mackall" <mpm@selenic.com>,
	"Herbert Xu" <herbert@gondor.apana.org.au>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Nicolas Saenz Julienne" <nsaenzjulienne@suse.de>,
	"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,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<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, 3 Mar 2021 11:16:47 -0800	[thread overview]
Message-ID: <3e90b354-cae3-50d4-601b-9c6c5ca60cb1@gmail.com> (raw)
In-Reply-To: <7B6F49A9-A31D-4126-8CB1-11EE3B2B7950@gmail.com>

On 3/3/21 6:06 AM, Álvaro Fernández Rojas wrote:
> Hi Philipp,
> 
>> El 3 mar 2021, a las 14:52, Philipp Zabel <p.zabel@pengutronix.de> escribió:
>>
>> 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.
> 
> In only added reset_control_rearm() because Florian requested it…
> I think it’s not needed, so we can use v3, since it was the only change between v3 and v4...

Not the first time I am confused by the reset API not sure if I will
ever get it one day, so apologies for suggesting something incorrect here.
-- 
Florian