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

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Date:   Thu, 12 Sep 2019 10:49:07 +0200
From:   Corentin Labbe <clabbe.montjoie@...il.com>
To:     Maxime Ripard <maxime.ripard@...ndra.org>
Cc:     davem@...emloft.net, herbert@...dor.apana.org.au,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <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 2/2] crypto: sun4i-ss: enable pm_runtime

On Thu, Sep 12, 2019 at 08:35:51AM +0200, Maxime Ripard wrote:
> Hi,
> 
> Le mer. 11 sept. 2019 à 13:46, Corentin Labbe
> <clabbe.montjoie@...il.com> a écrit :
> >
> > 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 |  5 +++
> >  drivers/crypto/sunxi-ss/sun4i-ss-core.c   | 42 ++++++++++++++++++++++-
> >  2 files changed, 46 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/crypto/sunxi-ss/sun4i-ss-cipher.c b/drivers/crypto/sunxi-ss/sun4i-ss-cipher.c
> > index fa4b1b47822e..1fedec9e83b0 100644
> > --- a/drivers/crypto/sunxi-ss/sun4i-ss-cipher.c
> > +++ b/drivers/crypto/sunxi-ss/sun4i-ss-cipher.c
> > @@ -10,6 +10,8 @@
> >   *
> >   * You could find the datasheet in Documentation/arm/sunxi.rst
> >   */
> > +
> > +#include <linux/pm_runtime.h>
> >  #include "sun4i-ss.h"
> >
> >  static int noinline_for_stack sun4i_ss_opti_poll(struct skcipher_request *areq)
> > @@ -497,13 +499,16 @@ int sun4i_ss_cipher_init(struct crypto_tfm *tfm)
> >                 return PTR_ERR(op->fallback_tfm);
> >         }
> >
> > +       pm_runtime_get_sync(op->ss->dev);
> >         return 0;
> >  }
> >
> >  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_sync(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 2c9ff01dddfc..5e6e1a308f60 100644
> > --- a/drivers/crypto/sunxi-ss/sun4i-ss-core.c
> > +++ b/drivers/crypto/sunxi-ss/sun4i-ss-core.c
> > @@ -14,6 +14,7 @@
> >  #include <linux/module.h>
> >  #include <linux/of.h>
> >  #include <linux/platform_device.h>
> > +#include <linux/pm_runtime.h>
> >  #include <crypto/scatterwalk.h>
> >  #include <linux/scatterlist.h>
> >  #include <linux/interrupt.h>
> > @@ -258,6 +259,37 @@ static int sun4i_ss_enable(struct sun4i_ss_ctx *ss)
> >         return err;
> >  }
> >
> > +#ifdef 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
> > +
> > +const struct dev_pm_ops sun4i_ss_pm_ops = {
> > +       SET_RUNTIME_PM_OPS(sun4i_ss_pm_suspend, sun4i_ss_pm_resume, NULL)
> > +};
> > +
> > +static void sun4i_ss_pm_init(struct sun4i_ss_ctx *ss)
> > +{
> > +       pm_runtime_use_autosuspend(ss->dev);
> > +       pm_runtime_set_autosuspend_delay(ss->dev, 1000);
> > +
> > +       pm_runtime_get_noresume(ss->dev);
> > +       pm_runtime_set_active(ss->dev);
> > +       pm_runtime_enable(ss->dev);
> > +}
> 
> It's not really clear to me what you're doing here? Can you explain?
> 

I set the autosuspend state and delay.

I say that the device is active and so I "get" it.
Then I enable PM.

I do like that since I use the device later in probe(), so I need to keep it up.
At the end of probe() I put the device which go in suspend automaticaly after.

Regards