Re: [PATCH v1 08/17] ACPI: processor: idle: Rework first-level _LPI states processing

On 7/9/2026 8:37 PM, Rafael J. Wysocki wrote:
> From: "Rafael J. Wysocki" <[email protected]>
>
> The first-level _LPI states need not be combined with the previous
> level and the entry method for them cannot be ACPI_CSTATE_INTEGER, so
> process them directly in acpi_processor_get_lpi_info() instead of doing
> a special case for them in flatten_lpi_states().
>
> Also bail out if there are no _LPI states at the first level because
> that means that there are no _LPI states at all.
>
> Signed-off-by: Rafael J. Wysocki <[email protected]>
> ---
>   drivers/acpi/processor_idle.c | 47 +++++++++++++++++++++++++++--------
>   1 file changed, 37 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> index e990a43514e6..efd3e76377fa 100644
> --- a/drivers/acpi/processor_idle.c
> +++ b/drivers/acpi/processor_idle.c
> @@ -1068,13 +1068,6 @@ static unsigned int flatten_lpi_states(struct acpi_processor *pr,
>   
>   		flpi = &pr->power.lpi_states[flat_state_cnt];
>   
> -		if (!prev_level) { /* leaf/processor node */
> -			memcpy(flpi, t, sizeof(*t));
> -			stash_composite_state(curr_level, flpi);
> -			flat_state_cnt++;
> -			continue;
> -		}
> -
>   		for (i = 0; i < prev_level->composite_states_size; i++) {
>   			p = prev_level->composite_states[i];
>   			if (t->index <= p->enable_parent_state &&
> @@ -1101,9 +1094,10 @@ static int acpi_processor_get_lpi_info(struct acpi_processor *pr)
>   {
>   	struct acpi_lpi_states_array info[2], *prev, *curr;
>   	acpi_handle handle = pr->handle;
> -	unsigned int state_count;
> +	unsigned int state_count = 0;
>   	acpi_status status;
> -	int ret, i;
> +	unsigned int i;
> +	int ret;
>   
>   	/* make sure our architecture has support */
>   	ret = acpi_processor_ffh_lpi_probe(pr->id);
> @@ -1117,12 +1111,45 @@ static int acpi_processor_get_lpi_info(struct acpi_processor *pr)
>   		return -EINVAL;
>   
>   	curr = &info[0];
> +	curr->composite_states_size = 0;
>   
>   	ret = acpi_processor_evaluate_lpi(handle, curr);
>   	if (ret)
>   		return ret;
>   
> -	state_count = flatten_lpi_states(pr, 0, curr, NULL);
> +	/* Copy all of the usable first-level states to power.lpi_states[]. */
> +	for (i = 0; i < curr->size; i++) {
> +		struct acpi_lpi_state *lpi = &curr->entries[i];
> +		struct acpi_lpi_state *flpi;
> +
> +		/*
> +		 * Skip states that are not enabled or have an inadequate entry
> +		 * method for this level.
> +		 */
> +		if (!(lpi->flags & ACPI_LPI_STATE_FLAGS_ENABLED) ||
> +		    lpi->entry_method == ACPI_CSTATE_INTEGER)
> +			continue;
> +
> +		if (state_count >= ACPI_PROCESSOR_MAX_POWER) {
> +			acpi_handle_info(handle,
> +					 "No space for more _LPI states than %d\n",
> +					 ACPI_PROCESSOR_MAX_POWER);
> +			break;
> +		}
> +
> +		flpi = &pr->power.lpi_states[state_count++];
> +		memcpy(flpi, lpi, sizeof(*lpi));
> +		stash_composite_state(curr, flpi);
> +	}
> +
> +	kfree(curr->entries);
> +
> +	/*
> +	 * If there are no _LPI states at the first level, there are no _LPI
> +	 * states at all.
> +	 */
> +	if (!state_count)
> +		return -ENODATA;
>   
The code is easier to understand after this rework.
But the "first level" is not good to me.
IIUC, the first level is processor, right?
In addition, how about extract a function, like, 
flatten_processor_lpi_states, for these codes?
>   	prev = curr;
>   	curr = &info[1];