Re: [PATCH v1 4/4] board: verdin-am62: set cpu core voltage depending on speed grade

[Max Krummenacher <max.oss.09@gmail.com>]

On Wed, Jan 17, 2024 at 11:16:49AM +0100, Max Krummenacher wrote:
> From: Max Krummenacher <max.krummenacher@toradex.com>
> 
> Speed grade T requires the VDD_CORE voltage to be 0.85V if using
> the maximum core frequency.
> 
> Speed grades G, K, S allow the VDD_CORE voltage to be 0.75V up to the
> maximum core frequency but allow to run at 0.85V.
> 
> For efficiency in manufacturing and code maintenance we use 0.85V for
> the PMIC defaults and device tree settings and dynamically adjust the
> voltage in the PMIC and device tree to 0.75V for lower speed SKU to
> gain more than 100mW power consumption reduction.
> 
> Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
> ---
> 
>  board/toradex/verdin-am62/verdin-am62.c | 47 +++++++++++++++++++++++++
>  1 file changed, 47 insertions(+)
> 
> diff --git a/board/toradex/verdin-am62/verdin-am62.c b/board/toradex/verdin-am62/verdin-am62.c
> index 4e912b5f32f..8b9db224069 100644
> --- a/board/toradex/verdin-am62/verdin-am62.c
> +++ b/board/toradex/verdin-am62/verdin-am62.c
> @@ -13,10 +13,13 @@
>  #include <fdt_support.h>
>  #include <init.h>
>  #include <k3-ddrss.h>
> +#include <power/regulator.h>

In the !DM_REGULATOR case regulator.h assumes errno.h to be already included.
This happens when compiling the R5 SPL.

Will fix this in a v2 of the series.

Max

>  #include <spl.h>
>  
>  #include "../common/tdx-cfg-block.h"
>  
> +#define VDD_CORE_REG "buck1"
> +
>  DECLARE_GLOBAL_DATA_PTR;
>  
>  int board_init(void)
> @@ -49,9 +52,37 @@ int board_fit_config_name_match(const char *name)
>  }
>  #endif
>  
> +static u32 get_vdd_core_nominal(void)
> +{
> +	int core_uvolt;
> +
> +	switch (k3_get_speed_grade()) {
> +	case 'G':
> +	case 'K':
> +	case 'S':
> +		core_uvolt = 750000;
> +		break;
> +	case 'T':
> +	default:
> +		core_uvolt = 850000;
> +		break;
> +	}
> +	return core_uvolt;
> +}
> +
>  #if IS_ENABLED(CONFIG_OF_LIBFDT) && IS_ENABLED(CONFIG_OF_BOARD_SETUP)
>  int ft_board_setup(void *blob, struct bd_info *bd)
>  {
> +	int core_uvolt;
> +
> +	core_uvolt = get_vdd_core_nominal();
> +	if (core_uvolt != 850000) {
> +		do_fixup_by_path_u32(blob, "/bus@f0000/i2c@20000000/pmic@30/regulators/buck1",
> +				     "regulator-max-microvolt", core_uvolt, 0);
> +		do_fixup_by_path_u32(blob, "/bus@f0000/i2c@20000000/pmic@30/regulators/buck1",
> +				     "regulator-min-microvolt", core_uvolt, 0);
> +	}
> +
>  	return ft_common_board_setup(blob, bd);
>  }
>  #endif
> @@ -86,6 +117,22 @@ static void select_dt_from_module_version(void)
>  
>  int board_late_init(void)
>  {
> +	int ret;
> +	int core_uvolt;
> +	struct udevice *dev = NULL;
> +
> +	core_uvolt = get_vdd_core_nominal();
> +	if (core_uvolt != 850000) {
> +		/* Set CPU core voltage to 0.75V for slower speed grades */
> +		ret = regulator_get_by_devname(VDD_CORE_REG, &dev);
> +		if (ret)
> +			pr_err("VDD CORE Regulator get error: %d\n", ret);
> +
> +		ret = regulator_set_value_force(dev, core_uvolt);
> +		if (ret)
> +			pr_err("VDD CORE Regulator value setting error: %d\n", ret);
> +	}
> +
>  	select_dt_from_module_version();
>  
>  	return 0;
> -- 
> 2.42.0
>