Re: [RFC v4 3/4] platform/x86/amd: dptc: Add platform profile support

[Mario Limonciello <mario.limonciello@amd.com>]

On 3/9/2026 3:51 PM, Antheas Kapenekakis wrote:
> Register a platform_profile handler so the driver exposes standard
> power profiles (low-power, balanced, performance) alongside the manual
> tunable interface.
> 
> When a non-custom profile is active, parameter writes are blocked
> (-EBUSY) and current_value reflects the profile's preset values.
> Selecting the "custom" profile returns control to the user for manual
> staging and committing. On resume, the active profile is automatically
> re-applied.
> 
> Assisted-by: Claude:claude-opus-4-6
> Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
> ---
>   drivers/platform/x86/amd/Kconfig |   1 +
>   drivers/platform/x86/amd/dptc.c  | 109 ++++++++++++++++++++++++++++++-
>   2 files changed, 108 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/platform/x86/amd/Kconfig b/drivers/platform/x86/amd/Kconfig
> index d610092467fc..41ffbd722524 100644
> --- a/drivers/platform/x86/amd/Kconfig
> +++ b/drivers/platform/x86/amd/Kconfig
> @@ -48,6 +48,7 @@ config AMD_ISP_PLATFORM
>   config AMD_DPTC
>   	tristate "AMD Dynamic Power and Thermal Configuration Interface (DPTCi)"
>   	depends on X86_64 && ACPI && DMI
> +	select ACPI_PLATFORM_PROFILE
>   	select FIRMWARE_ATTRIBUTES_CLASS
>   	help
>   	  Driver for AMD AGESA ALIB Function 0x0C, the Dynamic Power and

Your description doesn't talk about platform profile (which I expect is 
what the default should be for 99% of people).

> diff --git a/drivers/platform/x86/amd/dptc.c b/drivers/platform/x86/amd/dptc.c
> index b884cdfa3f82..f4db95affb1b 100644
> --- a/drivers/platform/x86/amd/dptc.c
> +++ b/drivers/platform/x86/amd/dptc.c
> @@ -23,6 +23,7 @@
>   #include <linux/module.h>
>   #include <linux/mutex.h>
>   #include <linux/platform_device.h>
> +#include <linux/platform_profile.h>
>   #include <linux/processor.h>
>   #include <linux/sysfs.h>
>   #include <linux/unaligned.h>
> @@ -56,8 +57,13 @@ struct dptc_param_limits {
>   	u32 expanded_max;
>   };
>   
> +struct dptc_profile {
> +	u32 vals[DPTC_NUM_PARAMS];	/* 0 = don't set / unstage this param */
> +};
> +
>   struct dptc_device_limits {
>   	struct dptc_param_limits params[DPTC_NUM_PARAMS];
> +	struct dptc_profile profiles[PLATFORM_PROFILE_LAST];
>   };
>   
>   struct dptc_param_desc {
> @@ -88,6 +94,11 @@ static const struct dptc_device_limits limits_maxhh = {
>   		[DPTC_PPT_PL3_FPPT] = {  1,  4, 40,  85, 100 },
>   		[DPTC_CPU_TEMP]     = { 60, 70, 95,  95, 100 },
>   	},
> +	.profiles = {
> +		[PLATFORM_PROFILE_LOW_POWER]   = { .vals = { 15, 15, 25, 0 } },
> +		[PLATFORM_PROFILE_BALANCED]    = { .vals = { 25, 27, 40, 0 } },
> +		[PLATFORM_PROFILE_PERFORMANCE] = { .vals = { 60, 63, 85, 0 } },
> +	},
>   };
>   
>   /* Substring matches against boot_cpu_data.x86_model_id; order matters. */
> @@ -139,11 +150,14 @@ struct dptc_priv {
>   
>   	bool expanded;
>   
> +	enum platform_profile_option profile;
> +	struct device *ppdev;
> +
>   	enum dptc_save_mode save_mode;
>   
>   	u32 staged[DPTC_NUM_PARAMS];
>   
> -	/* Protects staged, expanded, and save_mode */
> +	/* Protects staged, expanded, save_mode, and profile */
>   	struct mutex lock;
>   
>   	struct dptc_attr_sysfs params[DPTC_NUM_PARAMS];
> @@ -271,6 +285,14 @@ static ssize_t dptc_current_value_show(struct kobject *kobj,
>   
>   	guard(mutex)(&dptc->lock);
>   
> +	if (dptc->profile != PLATFORM_PROFILE_CUSTOM) {
> +		u32 val = dptc->dev_limits->profiles[dptc->profile].vals[ps->idx];
> +
> +		if (!val)
> +			return sysfs_emit(buf, "\n");
> +		return sysfs_emit(buf, "%u\n", val);
> +	}
> +
>   	if (!dptc->staged[ps->idx])
>   		return sysfs_emit(buf, "\n");
>   	return sysfs_emit(buf, "%u\n", dptc->staged[ps->idx]);
> @@ -288,6 +310,9 @@ static ssize_t dptc_current_value_store(struct kobject *kobj,
>   
>   	guard(mutex)(&dptc->lock);
>   
> +	if (dptc->profile != PLATFORM_PROFILE_CUSTOM)
> +		return -EBUSY;
> +
>   	if (count == 1 && buf[0] == '\n') {
>   		dptc->staged[ps->idx] = 0;
>   		return count;
> @@ -425,6 +450,9 @@ static ssize_t dptc_expanded_current_value_store(struct kobject *kobj,
>   
>   	guard(mutex)(&dptc->lock);
>   
> +	if (dptc->profile != PLATFORM_PROFILE_CUSTOM)
> +		return -EBUSY;
> +
>   	dptc->expanded = val;
>   	/* Clear staged values: limits changed, old values may be out of range */
>   	memset(dptc->staged, 0, sizeof(dptc->staged));
> @@ -593,6 +621,75 @@ static void dptc_kset_unregister(void *data)
>   	kset_unregister(data);
>   }
>   
> +/* Platform profile */
> +
> +static int dptc_apply_profile(struct dptc_priv *dptc,
> +			      enum platform_profile_option profile)
> +{
> +	const struct dptc_profile *pp;
> +	int i;
> +
> +	memset(dptc->staged, 0, sizeof(dptc->staged));
> +
> +	if (profile == PLATFORM_PROFILE_CUSTOM)
> +		return 0;
> +
> +	pp = &dptc->dev_limits->profiles[profile];
> +	for (i = 0; i < DPTC_NUM_PARAMS; i++) {
> +		if (!pp->vals[i])
> +			continue;
> +		dptc->staged[i] = pp->vals[i];
> +	}
> +
> +	return dptc_alib_save(dptc);
> +}
> +
> +static int dptc_pp_probe(void *drvdata, unsigned long *choices)
> +{
> +	struct dptc_priv *dptc = drvdata;
> +	int i, j;
> +
> +	set_bit(PLATFORM_PROFILE_CUSTOM, choices);
> +	for (i = 0; i < PLATFORM_PROFILE_LAST; i++) {
> +		for (j = 0; j < DPTC_NUM_PARAMS; j++) {
> +			if (dptc->dev_limits->profiles[i].vals[j]) {
> +				set_bit(i, choices);
> +				break;
> +			}
> +		}
> +	}
> +	return 0;
> +}
> +
> +static int dptc_pp_get(struct device *dev,
> +		       enum platform_profile_option *profile)
> +{
> +	struct dptc_priv *dptc = dev_get_drvdata(dev);
> +
> +	guard(mutex)(&dptc->lock);
> +
> +	*profile = dptc->profile;
> +	return 0;
> +}
> +
> +static int dptc_pp_set(struct device *dev,
> +		       enum platform_profile_option profile)
> +{
> +	struct dptc_priv *dptc = dev_get_drvdata(dev);
> +
> +	guard(mutex)(&dptc->lock);
> +
> +	dptc->profile = profile;
> +
> +	return dptc_apply_profile(dptc, profile);
> +}
> +
> +static const struct platform_profile_ops dptc_pp_ops = {
> +	.probe       = dptc_pp_probe,
> +	.profile_get = dptc_pp_get,
> +	.profile_set = dptc_pp_set,
> +};
> +
>   static int dptc_resume(struct device *dev)
>   {
>   	struct dptc_priv *dptc = dev_get_drvdata(dev);
> @@ -601,7 +698,9 @@ static int dptc_resume(struct device *dev)
>   	guard(mutex)(&dptc->lock);
>   
>   	/* In bulk mode, do not use pm ops for userspace flexibility. */
> -	if (dptc->save_mode == SAVE_SINGLE)
> +	if (dptc->profile != PLATFORM_PROFILE_CUSTOM)
> +		ret = dptc_apply_profile(dptc, dptc->profile);
> +	else if (dptc->save_mode == SAVE_SINGLE)
>   		ret = dptc_alib_save(dptc);
>   	else
>   		ret = 0;
> @@ -679,6 +778,12 @@ static int dptc_probe(struct platform_device *pdev)
>   	if (ret)
>   		return ret;
>   
> +	dptc->profile = PLATFORM_PROFILE_CUSTOM;
> +	dptc->ppdev = devm_platform_profile_register(dev, "amd-dptc", dptc,
> +						     &dptc_pp_ops);
> +	if (IS_ERR(dptc->ppdev))
> +		return PTR_ERR(dptc->ppdev);
> +
>   	return 0;
>   }
>