linux-kernel - Re: [PATCH 1/2] crypto: caam: Change the i.MX8MQ check support all i.MX8M variants

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Message-ID: <d82428e3-326b-db80-2e40-4ef1bdbca060@kontron.de>
Date:   Wed, 11 Dec 2019 14:23:32 +0000
From:   Schrempf Frieder <frieder.schrempf@...tron.de>
To:     Horia Geanta <horia.geanta@....com>, Adam Ford <aford173@...il.com>
CC:     "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "Mark Rutland" <mark.rutland@....com>,
        Aymen Sghaier <aymen.sghaier@....com>,
        "Fabio Estevam" <festevam@...il.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        dl-linux-imx <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/2] crypto: caam: Change the i.MX8MQ check support all
 i.MX8M variants

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@...tron.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@...il.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.

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

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

Thanks,
Frieder