Re: [PATCH v1] ACPI: PM: s2idle: Enable Low-Power S0 Idle MSFT UUID for non-AMD systems

[Mario Limonciello]

On 2/6/2024 13:33, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> Systems based on Intel platforms that use the MSFT UUID for Low-Power S0
> Idle (LPS0) have started to ship, so allow the kernel to use the MSFT
> UUID in the non-AMD case too, but in that case make it avoid evaluating
> the same _DSM function for two different UUIDs and prioritize the MSFT
> one.
>
> While at it, combine two MSFT _DSM function mask checks in
> acpi_s2idle_restore_early() so as to make it reflect the
> acpi_s2idle_prepare_late() flow more closely and adjust the
> Modern Standby entry and exit comments slightly.
>
> Non-AMD systems that do not support MSFT UUID for Low-power S0 Idle are
> not expected to be affected by this change in any way.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Reviewed-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> ---
>   drivers/acpi/x86/s2idle.c |   37 +++++++++++++++++++++++++++----------
>   1 file changed, 27 insertions(+), 10 deletions(-)
>
> Index: linux-pm/drivers/acpi/x86/s2idle.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/x86/s2idle.c
> +++ linux-pm/drivers/acpi/x86/s2idle.c
> @@ -488,7 +488,21 @@ static int lps0_device_attach(struct acp
>   		rev_id = 1;
>   		lps0_dsm_func_mask = validate_dsm(adev->handle,
>   					ACPI_LPS0_DSM_UUID, rev_id, &lps0_dsm_guid);
> -		lps0_dsm_func_mask_microsoft = -EINVAL;
> +		if (lps0_dsm_func_mask > 0 && lps0_dsm_func_mask_microsoft > 0) {
> +			unsigned int func_mask;
> +
> +			/*
> +			 * Avoid evaluating the same _DSM function for two
> +			 * different UUIDs and prioritize the MSFT one.
> +			 */
> +			func_mask = lps0_dsm_func_mask & lps0_dsm_func_mask_microsoft;
> +			if (func_mask) {
> +				acpi_handle_info(adev->handle,
> +						 "Duplicate LPS0 _DSM functions (mask: 0x%x)\n",
> +						 func_mask);
> +				lps0_dsm_func_mask &= ~func_mask;
> +			}
> +		}
>   	}
>   
>   	if (lps0_dsm_func_mask < 0 && lps0_dsm_func_mask_microsoft < 0)
> @@ -549,19 +563,22 @@ int acpi_s2idle_prepare_late(void)
>   				lps0_dsm_func_mask_microsoft, lps0_dsm_guid_microsoft);
>   
>   	/* LPS0 entry */
> -	if (lps0_dsm_func_mask > 0)
> -		acpi_sleep_run_lps0_dsm(acpi_s2idle_vendor_amd() ?
> -					ACPI_LPS0_ENTRY_AMD :
> -					ACPI_LPS0_ENTRY,
> +	if (lps0_dsm_func_mask > 0 && acpi_s2idle_vendor_amd())
> +		acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY_AMD,
>   					lps0_dsm_func_mask, lps0_dsm_guid);
> +
>   	if (lps0_dsm_func_mask_microsoft > 0) {
> -		/* modern standby entry */
> +		/* Modern Standby entry */
>   		acpi_sleep_run_lps0_dsm(ACPI_LPS0_MS_ENTRY,
>   				lps0_dsm_func_mask_microsoft, lps0_dsm_guid_microsoft);
>   		acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY,
>   				lps0_dsm_func_mask_microsoft, lps0_dsm_guid_microsoft);
>   	}
>   
> +	if (lps0_dsm_func_mask > 0 && !acpi_s2idle_vendor_amd())
> +		acpi_sleep_run_lps0_dsm(ACPI_LPS0_ENTRY,
> +					lps0_dsm_func_mask, lps0_dsm_guid);
> +
>   	list_for_each_entry(handler, &lps0_s2idle_devops_head, list_node) {
>   		if (handler->prepare)
>   			handler->prepare();
> @@ -600,14 +617,14 @@ void acpi_s2idle_restore_early(void)
>   					ACPI_LPS0_EXIT_AMD :
>   					ACPI_LPS0_EXIT,
>   					lps0_dsm_func_mask, lps0_dsm_guid);
> -	if (lps0_dsm_func_mask_microsoft > 0)
> +
> +	if (lps0_dsm_func_mask_microsoft > 0) {
>   		acpi_sleep_run_lps0_dsm(ACPI_LPS0_EXIT,
>   				lps0_dsm_func_mask_microsoft, lps0_dsm_guid_microsoft);
> -
> -	/* Modern standby exit */
> -	if (lps0_dsm_func_mask_microsoft > 0)
> +		/* Modern Standby exit */
>   		acpi_sleep_run_lps0_dsm(ACPI_LPS0_MS_EXIT,
>   				lps0_dsm_func_mask_microsoft, lps0_dsm_guid_microsoft);
> +	}
>   
>   	/* Screen on */
>   	if (lps0_dsm_func_mask_microsoft > 0)