Re: [PATCH] ARM: i.MX93: ele: start TRNG on i.MX93 rev a1

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello Sascha,

On 11.03.24 09:06, Sascha Hauer wrote:
> On i.MX93 a0 the TRNG seems to be started automatically. On rev a1 it's
> not and OP-TEE panics with "Cannot retrieve random data from ELE". Start
> the TRNG to let OP-TEE startup successfully.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  arch/arm/mach-imx/ele.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/arch/arm/mach-imx/ele.c b/arch/arm/mach-imx/ele.c
> index ab3958cbd3..f8093fc694 100644
> --- a/arch/arm/mach-imx/ele.c
> +++ b/arch/arm/mach-imx/ele.c
> @@ -165,6 +165,23 @@ int ele_get_info(struct ele_get_info_data *info)
>  	return ret;
>  }
>  
> +static int ele_get_start_trng(void)
> +{
> +        struct ele_msg msg = {

strange indentation.

> +		.version = ELE_VERSION,
> +		.tag = ELE_CMD_TAG,
> +		.size = 1,
> +		.command = ELE_START_RNG,
> +	};
> +	int ret;
> +
> +	ret = ele_call(&msg);
> +	if (ret)
> +		pr_err("Could not start TRNG, response 0x%x\n", msg.data[0]);
> +
> +	return ret;
> +}
> +
>  int imx93_ele_load_fw(void *bl33)
>  {
>  	struct ele_get_info_data info = {};
> @@ -204,6 +221,9 @@ int imx93_ele_load_fw(void *bl33)
>  		pr_err("Could not start ELE firmware: ret %d, response 0x%x\n",
>  			ret, msg.data[0]);
>  
> +	if (rev == 0xa1)
> +		ele_get_start_trng();

Does it hurt to start it unconditionally, even if it's already enabled?
At the least, I'd prefer this to be rev >= 0xa1, so it need not be debugged
again in the future.

Thoughts?

Ahmad

> +
>  	return 0;
>  }
>  

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