Re: [PATCH] ARM: i.MX8MP-EVK: increase VDD_ARM to OD voltage

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

Hello Lucas,

On 06.02.23 21:59, Lucas Stach wrote:
> The Linux kernel or whatever is started from Barebox might switch the
> ARM frequency to OD level, without first reprogramming the PMIC as
> required. This might lead to system instability. To avoid this,
> increase VDD_ARM to OD level. When the kernel handles the PMIC properly
> it will drop the voltage back to ND level when appropriate.
> 
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> ---
>  arch/arm/boards/nxp-imx8mp-evk/lowlevel.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/arm/boards/nxp-imx8mp-evk/lowlevel.c b/arch/arm/boards/nxp-imx8mp-evk/lowlevel.c
> index 3cb24df1ca3f..d6fc32e65b61 100644
> --- a/arch/arm/boards/nxp-imx8mp-evk/lowlevel.c
> +++ b/arch/arm/boards/nxp-imx8mp-evk/lowlevel.c
> @@ -61,6 +61,12 @@ static struct pmic_config pca9450_cfg[] = {
>  	{ PCA9450_BUCK1OUT_DVS0, 0x1C },
>  	{ PCA9450_BUCK1OUT_DVS1, 0x14 },
>  	{ PCA9450_BUCK1CTRL, 0x59 },
> +	/*
> +	 * Increase VDD_ARM to 0.95V to avoid issues in case software after
> +	 * Barebox switches to the OD ARM frequency without reprogramming the
> +	 * PMIC first.
> +	 */
> +	{ PCA9450_BUCK2OUT_DVS0, 0x1C },

We use the same PMIC on nxp-imx8mn-evk and newer nxp-imx8mm-evk
as well. Should we do this there too? Do we need to change something
for the i.MX8M boards using Rohm PMICs?

>  	/* set WDOG_B_CFG to cold reset */
>  	{ PCA9450_RESET_CTRL, 0xA1 },
>  };

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |