From: Nicolas Ferre Subject: Re: [PATCH v1] char: hw_random: atmel-rng: disable TRNG during suspend Date: Mon, 24 Oct 2016 14:07:18 +0200 Message-ID: References: <1477296208-28335-1-git-send-email-wenyou.yang@atmel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit Cc: , Wenyou Yang , To: Wenyou Yang , Herbert Xu , Matt Mackall Return-path: Received: from eusmtp01.atmel.com ([212.144.249.243]:32278 "EHLO eusmtp01.atmel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756858AbcJXMHV (ORCPT ); Mon, 24 Oct 2016 08:07:21 -0400 In-Reply-To: <1477296208-28335-1-git-send-email-wenyou.yang@atmel.com> Sender: linux-crypto-owner@vger.kernel.org List-ID: Le 24/10/2016 ? 10:03, Wenyou Yang a ?crit : > To fix the over consumption on the VDDCore due to the TRNG enabled, > disable the TRNG during suspend, not only disable the user interface > clock (which is controlled by PMC). Because the user interface clock > is independent from any clock that may be used in the entropy source > logic circuitry. > > Signed-off-by: Wenyou Yang > --- > > drivers/char/hw_random/atmel-rng.c | 16 ++++++++++++++-- > 1 file changed, 14 insertions(+), 2 deletions(-) > > diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c > index 0fcc9e6..2e2d09a 100644 > --- a/drivers/char/hw_random/atmel-rng.c > +++ b/drivers/char/hw_random/atmel-rng.c > @@ -48,6 +48,16 @@ static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max, > return 0; > } > > +static void atmel_trng_enable(struct atmel_trng *trng) > +{ > + writel(TRNG_KEY | 1, trng->base + TRNG_CR); > +} > + > +static void atmel_trng_disable(struct atmel_trng *trng) > +{ > + writel(TRNG_KEY, trng->base + TRNG_CR); > +} > + > static int atmel_trng_probe(struct platform_device *pdev) > { > struct atmel_trng *trng; > @@ -71,7 +81,7 @@ static int atmel_trng_probe(struct platform_device *pdev) > if (ret) > return ret; > > - writel(TRNG_KEY | 1, trng->base + TRNG_CR); > + atmel_trng_enable(trng); > trng->rng.name = pdev->name; > trng->rng.read = atmel_trng_read; > > @@ -94,7 +104,7 @@ static int atmel_trng_remove(struct platform_device *pdev) > > hwrng_unregister(&trng->rng); > > - writel(TRNG_KEY, trng->base + TRNG_CR); > + atmel_trng_disable(trng); > clk_disable_unprepare(trng->clk); > > return 0; > @@ -105,6 +115,7 @@ static int atmel_trng_suspend(struct device *dev) > { > struct atmel_trng *trng = dev_get_drvdata(dev); > > + atmel_trng_disable(trng); > clk_disable_unprepare(trng->clk); > > return 0; > @@ -114,6 +125,7 @@ static int atmel_trng_resume(struct device *dev) > { > struct atmel_trng *trng = dev_get_drvdata(dev); > > + atmel_trng_enable(trng); > return clk_prepare_enable(trng->clk); Isn't it the other way around: enable the user interface first, then enable the internal clock? like: clk_prepare_enable(trng->clk); atmel_trng_enable(trng); Regards, -- Nicolas Ferre