[PATCH v1] char: hw_random: atmel-rng: disable TRNG during suspend

[Nicolas Ferre]

Le 24/10/2016 à 10:03, Wenyou Yang a écrit :
> 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 <wenyou.yang at atmel.com>
> ---
> 
>  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