linux-kernel - Re: HRNG in CAAM isn't working properly on IMX6 SoloX

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Date:   Mon, 10 Jan 2022 13:28:54 -0300
From:   Fabio Estevam <festevam@...il.com>
To:     Fredrik Yhlen <fredrik.yhlen@...ian.se>,
        Horia Geanta Neag <horia.geanta@....com>
Cc:     Aymen Sghaier <aymen.sghaier@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Andrey Smirnov <andrew.smirnov@...il.com>,
        Heiko Schocher <hs@...x.de>
Subject: Re: HRNG in CAAM isn't working properly on IMX6 SoloX

Hi Horia,

On Mon, Aug 30, 2021 at 8:49 AM Fabio Estevam <festevam@...il.com> wrote:

> We also observe this issue.
>
> Heiko on Cc tried increasing the RTSDCTL_ENT_DLY_MIN value
> and this seems to help:
>
> diff --git a/drivers/crypto/caam/regs.h b/drivers/crypto/caam/regs.h
> index af61f3a2c0d4..53c9fa04a24c 100644
> --- a/drivers/crypto/caam/regs.h
> +++ b/drivers/crypto/caam/regs.h
> @@ -513,7 +513,7 @@ struct rng4tst {
>   };
>  #define RTSDCTL_ENT_DLY_SHIFT 16
>  #define RTSDCTL_ENT_DLY_MASK (0xffff << RTSDCTL_ENT_DLY_SHIFT)
> -#define RTSDCTL_ENT_DLY_MIN 3200
> +#define RTSDCTL_ENT_DLY_MIN 4800
>  #define RTSDCTL_ENT_DLY_MAX 12800
>   u32 rtsdctl; /* seed control register */
>   union {

Even with the change above we get the following errors on a
imx6sx-based board running 5.10.y:

[    0.918126] caam 2100000.crypto: registering rng-caam
[   22.598192] caam_jr 2101000.jr: 2000025b: CCB: desc idx 2: RNG:
Hardware error
[   22.598260] caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG:
Hardware error
[   22.598324] caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG:
Hardware error
[   22.598368] caam_jr 2101000.jr: 20003c5b: CCB: desc idx 60: RNG:
Hardware error

What is the proper way to fix this issue?

Thanks,

Fabio Estevam