linux-kernel - Re: [PATCH v2 2/2] crypto: sun4i-ss: enable pm

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Date:   Mon, 23 Sep 2019 09:53:24 +0200
From:   Corentin Labbe <clabbe.montjoie@...il.com>
To:     Maxime Ripard <mripard@...nel.org>
Cc:     davem@...emloft.net, herbert@...dor.apana.org.au, wens@...e.org,
        linux-arm-kernel@...ts.infradead.org, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH v2 2/2] crypto: sun4i-ss: enable pm_runtime

On Thu, Sep 19, 2019 at 06:55:59PM +0200, Maxime Ripard wrote:
> Hi,
> 
> On Thu, Sep 19, 2019 at 07:10:35AM +0200, Corentin Labbe wrote:
> > This patch enables power management on the Security System.
> >
> > Signed-off-by: Corentin Labbe <clabbe.montjoie@...il.com>
> > ---
> >  drivers/crypto/sunxi-ss/sun4i-ss-cipher.c |  9 +++
> >  drivers/crypto/sunxi-ss/sun4i-ss-core.c   | 94 +++++++++++++++++++----
> >  drivers/crypto/sunxi-ss/sun4i-ss-hash.c   | 12 +++
> >  drivers/crypto/sunxi-ss/sun4i-ss-prng.c   |  9 ++-
> >  drivers/crypto/sunxi-ss/sun4i-ss.h        |  2 +
> >  5 files changed, 110 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/crypto/sunxi-ss/sun4i-ss-cipher.c b/drivers/crypto/sunxi-ss/sun4i-ss-cipher.c
> > index fa4b1b47822e..c9799cbe0530 100644
> > --- a/drivers/crypto/sunxi-ss/sun4i-ss-cipher.c
> > +++ b/drivers/crypto/sunxi-ss/sun4i-ss-cipher.c
> > @@ -480,6 +480,7 @@ int sun4i_ss_cipher_init(struct crypto_tfm *tfm)
> >  	struct sun4i_tfm_ctx *op = crypto_tfm_ctx(tfm);
> >  	struct sun4i_ss_alg_template *algt;
> >  	const char *name = crypto_tfm_alg_name(tfm);
> > +	int err;
> >
> >  	memset(op, 0, sizeof(struct sun4i_tfm_ctx));
> >
> > @@ -497,13 +498,21 @@ int sun4i_ss_cipher_init(struct crypto_tfm *tfm)
> >  		return PTR_ERR(op->fallback_tfm);
> >  	}
> >
> > +	err = pm_runtime_get_sync(op->ss->dev);
> > +	if (err < 0)
> > +		goto error_pm;
> >  	return 0;
> 
> Newline here
> 
> > +error_pm:
> > +	crypto_free_sync_skcipher(op->fallback_tfm);
> > +	return err;
> >  }
> >
> >  void sun4i_ss_cipher_exit(struct crypto_tfm *tfm)
> >  {
> >  	struct sun4i_tfm_ctx *op = crypto_tfm_ctx(tfm);
> > +
> >  	crypto_free_sync_skcipher(op->fallback_tfm);
> > +	pm_runtime_put(op->ss->dev);
> >  }
> >
> >  /* check and set the AES key, prepare the mode to be used */
> > diff --git a/drivers/crypto/sunxi-ss/sun4i-ss-core.c b/drivers/crypto/sunxi-ss/sun4i-ss-core.c
> > index 6c2db5d83b06..311c2653a9c3 100644
> > --- a/drivers/crypto/sunxi-ss/sun4i-ss-core.c
> > +++ b/drivers/crypto/sunxi-ss/sun4i-ss-core.c
> > @@ -44,7 +44,8 @@ static struct sun4i_ss_alg_template ss_algs[] = {
> >  				.cra_blocksize = MD5_HMAC_BLOCK_SIZE,
> >  				.cra_ctxsize = sizeof(struct sun4i_req_ctx),
> >  				.cra_module = THIS_MODULE,
> > -				.cra_init = sun4i_hash_crainit
> > +				.cra_init = sun4i_hash_crainit,
> > +				.cra_exit = sun4i_hash_craexit
> 
> You should add a comma at the end to prevent having to modify it again
> 
> >  			}
> >  		}
> >  	}
> > @@ -70,7 +71,8 @@ static struct sun4i_ss_alg_template ss_algs[] = {
> >  				.cra_blocksize = SHA1_BLOCK_SIZE,
> >  				.cra_ctxsize = sizeof(struct sun4i_req_ctx),
> >  				.cra_module = THIS_MODULE,
> > -				.cra_init = sun4i_hash_crainit
> > +				.cra_init = sun4i_hash_crainit,
> > +				.cra_exit = sun4i_hash_craexit
> 
> Ditto
> 
> >  			}
> >  		}
> >  	}
> > @@ -262,6 +264,61 @@ static int sun4i_ss_enable(struct sun4i_ss_ctx *ss)
> >  	return err;
> >  }
> >
> > +/*
> > + * Power management strategy: The device is suspended unless a TFM exists for
> > + * one of the algorithms proposed by this driver.
> > + */
> > +#if defined(CONFIG_PM)
> > +static int sun4i_ss_pm_suspend(struct device *dev)
> > +{
> > +	struct sun4i_ss_ctx *ss = dev_get_drvdata(dev);
> > +
> > +	sun4i_ss_disable(ss);
> > +	return 0;
> > +}
> > +
> > +static int sun4i_ss_pm_resume(struct device *dev)
> > +{
> > +	struct sun4i_ss_ctx *ss = dev_get_drvdata(dev);
> > +
> > +	return sun4i_ss_enable(ss);
> > +}
> > +#endif
> > +
> 
> Why not just have the suspend and resume function and the enable /
> disable functions merged together, you're not using them directy as
> far as I can see.
> 
> > +const struct dev_pm_ops sun4i_ss_pm_ops = {
> > +	SET_RUNTIME_PM_OPS(sun4i_ss_pm_suspend, sun4i_ss_pm_resume, NULL)
> > +};
> > +
> > +/*
> > + * When power management is enabled, this function enables the PM and set the
> > + * device as suspended
> > + * When power management is disabled, this function just enables the device
> > + */
> > +static int sun4i_ss_pm_init(struct sun4i_ss_ctx *ss)
> > +{
> > +	int err;
> > +
> > +	pm_runtime_use_autosuspend(ss->dev);
> > +	pm_runtime_set_autosuspend_delay(ss->dev, 2000);
> > +
> > +	err = pm_runtime_set_suspended(ss->dev);
> > +	if (err)
> > +		return err;
> > +	pm_runtime_enable(ss->dev);
> > +#if !defined(CONFIG_PM)
> > +	err = sun4i_ss_enable(ss);
> > +#endif
> > +	return err;
> > +}
> 
> This looks nicer:
> https://elixir.bootlin.com/linux/latest/source/drivers/spi/spi-sun4i.c#L492
> 
> Or, just make it depend on CONFIG_PM, we should probably do it anyway
> at the ARCH level anyway.
> 

Hello

I usually prefer to give choice (PM vs not PM), but it simplify a lot the code to depend on PM, so I will go for it.

Thanks