Merge branches 'acpi-processor' and 'acpi-cppc'

Merge ACPI processor driver updates and ACPI CPPC library updates for
7.1-rc1:

 - Address multiple assorted issues and clean up the code in the ACPI
   processor idle driver (Huisong Li)

 - Replace strlcat() in the ACPI processor idle drive with a better
   alternative (Andy Shevchenko)

 - Rearrange and clean up acpi_processor_errata_piix4() (Rafael Wysocki)

 - Move reference performance to capabilities and fix an uninitialized
   variable in the ACPI CPPC library (Pengjie Zhang)

 - Add support for the Performance Limited Register to the ACPI CPPC
   library (Sumit Gupta)

 - Add cppc_get_perf() API to read performance controls, extend
   cppc_set_epp_perf() for FFH/SystemMemory, and make the ACPI CPPC
   library warn on missing mandatory DESIRED_PERF register (Sumit Gupta)

 - Modify the cpufreq CPPC driver to update MIN_PERF/MAX_PERF in target
   callbacks to allow it to control performance bounds via standard
   scaling_min_freq and scaling_max_freq sysfs attributes and add sysfs
   documentation for the Performance Limited Register to it (Sumit Gupta)

* acpi-processor:
  ACPI: processor: idle: Reset cpuidle on C-state list changes
  cpuidle: Extract and export no-lock variants of cpuidle_unregister_device()
  ACPI: processor: idle: Fix NULL pointer dereference in hotplug path
  ACPI: processor: idle: Reset power_setup_done flag on initialization failure
  ACPI: processor: Rearrange and clean up acpi_processor_errata_piix4()
  ACPI: processor: idle: Replace strlcat() with better alternative
  ACPI: processor: idle: Remove redundant static variable and rename cstate check function
  ACPI: processor: idle: Move max_cstate update out of the loop
  ACPI: processor: idle: Remove redundant cstate check in acpi_processor_power_init
  ACPI: processor: idle: Add missing bounds check in flatten_lpi_states()

* acpi-cppc:
  ACPI: CPPC: Check cpc_read() return values consistently
  ACPI: CPPC: Fix uninitialized ref variable in cppc_get_perf_caps()
  ACPI: CPPC: Move reference performance to capabilities
  cpufreq: CPPC: Add sysfs documentation for perf_limited
  ACPI: CPPC: add APIs and sysfs interface for perf_limited
  cpufreq: cppc: Update MIN_PERF/MAX_PERF in target callbacks
  cpufreq: CPPC: Update cached perf_ctrls on sysfs write
  ACPI: CPPC: Extend cppc_set_epp_perf() for FFH/SystemMemory
  ACPI: CPPC: Warn on missing mandatory DESIRED_PERF register
  ACPI: CPPC: Add cppc_get_perf() API to read performance controls

Author: rafaeljw

Documentation/ABI/testing/sysfs-devices-system-cpu

@@ -327,6 +327,24 @@ Description:	Energy performance preference
 
 		This file is only present if the cppc-cpufreq driver is in use.
 
+What:		/sys/devices/system/cpu/cpuX/cpufreq/perf_limited
+Date:		February 2026
+Contact:	linux-pm@vger.kernel.org
+Description:	Performance Limited
+
+		Read to check if platform throttling (thermal/power/current
+		limits) caused delivered performance to fall below the
+		requested level. A non-zero value indicates throttling occurred.
+
+		Write the bitmask of bits to clear:
+
+		  - 0x1 = clear bit 0 (desired performance excursion)
+		  - 0x2 = clear bit 1 (minimum performance excursion)
+		  - 0x3 = clear both bits
+
+		The platform sets these bits; OSPM can only clear them.
+
+		This file is only present if the cppc-cpufreq driver is in use.
 
 What:		/sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1}
 Date:		August 2008

drivers/acpi/acpi_processor.c

@@ -48,11 +48,6 @@ acpi_handle acpi_get_processor_handle(int cpu)
 
 static int acpi_processor_errata_piix4(struct pci_dev *dev)
 {
-	u8 value1 = 0;
-	u8 value2 = 0;
-	struct pci_dev *ide_dev = NULL, *isa_dev = NULL;
-
-
 	if (!dev)
 		return -EINVAL;
 
@@ -108,16 +103,16 @@ static int acpi_processor_errata_piix4(struct pci_dev *dev)
 		 * each IDE controller's DMA status to make sure we catch all
 		 * DMA activity.
 		 */
-		ide_dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
+		dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
 				     PCI_DEVICE_ID_INTEL_82371AB,
 				     PCI_ANY_ID, PCI_ANY_ID, NULL);
-		if (ide_dev) {
-			errata.piix4.bmisx = pci_resource_start(ide_dev, 4);
+		if (dev) {
+			errata.piix4.bmisx = pci_resource_start(dev, 4);
 			if (errata.piix4.bmisx)
-				dev_dbg(&ide_dev->dev,
+				dev_dbg(&dev->dev,
 					"Bus master activity detection (BM-IDE) erratum enabled\n");
 
-			pci_dev_put(ide_dev);
+			pci_dev_put(dev);
 		}
 
 		/*
@@ -129,18 +124,20 @@ static int acpi_processor_errata_piix4(struct pci_dev *dev)
 		 * disable C3 support if this is enabled, as some legacy
 		 * devices won't operate well if fast DMA is disabled.
 		 */
-		isa_dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
+		dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
 				     PCI_DEVICE_ID_INTEL_82371AB_0,
 				     PCI_ANY_ID, PCI_ANY_ID, NULL);
-		if (isa_dev) {
-			pci_read_config_byte(isa_dev, 0x76, &value1);
-			pci_read_config_byte(isa_dev, 0x77, &value2);
+		if (dev) {
+			u8 value1 = 0, value2 = 0;
+
+			pci_read_config_byte(dev, 0x76, &value1);
+			pci_read_config_byte(dev, 0x77, &value2);
 			if ((value1 & 0x80) || (value2 & 0x80)) {
 				errata.piix4.fdma = 1;
-				dev_dbg(&isa_dev->dev,
+				dev_dbg(&dev->dev,
 					"Type-F DMA livelock erratum (C3 disabled)\n");
 			}
-			pci_dev_put(isa_dev);
+			pci_dev_put(dev);
 		}
 
 		break;