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In-Reply-To: <d82428e3-326b-db80-2e40-4ef1bdbca060@kontron.de>
From:   Adam Ford <aford173@gmail.com>
Date:   Wed, 11 Dec 2019 08:27:16 -0600
Message-ID: <CAHCN7xKUSQQeGt984L9FXmXw7XFMqUvR+9RFqn-zv9q-zQdSSg@mail.gmail.com>
Subject: Re: [PATCH 1/2] crypto: caam: Change the i.MX8MQ check support all
 i.MX8M variants
To:     Schrempf Frieder <frieder.schrempf@kontron.de>
Cc:     Horia Geanta <horia.geanta@nxp.com>,
        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Aymen Sghaier <aymen.sghaier@nxp.com>,
        Fabio Estevam <festevam@gmail.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        dl-linux-imx <linux-imx@nxp.com>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Shawn Guo <shawnguo@kernel.org>,
        "David S. Miller" <davem@davemloft.net>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>
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On Wed, Dec 11, 2019 at 8:23 AM Schrempf Frieder
<frieder.schrempf@kontron.de> wrote:
>
> On 10.12.19 08:56, Horia Geanta wrote:
> > On 12/6/2019 9:55 PM, Adam Ford wrote:
> >> On Wed, Dec 4, 2019 at 5:38 AM Schrempf Frieder
> >> <frieder.schrempf@kontron.de> wrote:
> >>>
> >>> Hi Adam,
> >>>
> >>> On 30.11.19 23:51, Adam Ford wrote:
> >>>> The i.MX8M Mini uses the same crypto engine as the i.MX8MQ, but
> >>>> the driver is restricting the check to just the i.MX8MQ.
> >>>>
> >>>> This patch lets the driver support all i.MX8M Variants if enabled.
> >>>>
> >>>> Signed-off-by: Adam Ford <aford173@gmail.com>
> >>>
> >>> What about the following lines in run_descriptor_deco0()? Does this
> >>> condition also apply to i.MX8MM?
> >>
> >> I think that's a question for NXP.  I am not seeing that in the NXP
> >> Linux Release, and I don't have an 8MQ to compare.
> >>
> > IIRC the i.MX BSP releases use the JRI for initializing the RNG,
> > and not the DECO register interface.
> >
> >> I was able to get the driver working on the i.MXMM with the patch.
> >>
> > You are probably using a newer U-boot, which includes
> > commit dfaec76029f2 ("crypto/fsl: instantiate all rng state handles")
> >
> >> NXP  Team,
> >>
> >> Do you have any opinions on this?
> >>
> > Since current U-boot initializes both RNG state handles, practically
> > instantiate_rng() is a no-op.
> >
> > A simple experiment is to "lie" about the state_handle_mask, to exercise
> > the DECO acquire code (or, as mentioned above, to run with an older U-boot):
> >
> > @@ -268,12 +272,19 @@ static int instantiate_rng(struct device *ctrldev, int state_handle_mask,
> >          struct caam_ctrl __iomem *ctrl;
> >          u32 *desc, status = 0, rdsta_val;
> >          int ret = 0, sh_idx;
> > +       static int force_init = 1;
> >
> >          ctrl = (struct caam_ctrl __iomem *)ctrlpriv->ctrl;
> >          desc = kmalloc(CAAM_CMD_SZ * 7, GFP_KERNEL);
> >          if (!desc)
> >                  return -ENOMEM;
> >
> > +       if (force_init && (state_handle_mask == 0x3)) {
> > +               dev_err(ctrldev, "Forcing reinit of RNG state handle 0!\n");
> > +               force_init = 0;
> > +               state_handle_mask = 0x2;
> > +       }
> > +
> >          for (sh_idx = 0; sh_idx < RNG4_MAX_HANDLES; sh_idx++) {
> >                  /*
> >                   * If the corresponding bit is set, this state handle
> >
> > In this case boot log confirms the DECO cannot be acquired:
> > [    2.137101] caam 30900000.crypto: Forcing reinit of RNG state handle 0!
> > [    2.172293] caam 30900000.crypto: failed to acquire DECO 0
> > [    2.177786] caam 30900000.crypto: failed to instantiate RNG
> >
> > To sum up, writing to DECORSR is mandatory.
>
> Thanks Horia for providing the details.

I appreciate it too.

>
> Adam, can you update your patch to enable the code in
> run_descriptor_deco0() for i.MX8MM?

I will work on that.  I have been trying to get the mainline U-Boot to
start correctly, because I wanted to see if/how this interacted. I'll
try to get a V2 pushed today.

>
> If I understand this correctly, this is necessary to have the RNG
> initialize correctly no matter what version of U-Boot is used.

That makes sense based on Horia's feedback.  With the holidays this
month, my spare time and weekends have been full.

adam
>
> Thanks,
> Frieder