3 files changed, 32 insertions, 15 deletions

diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
index e07782b1fbb6..eaea733b368a 100644
--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -73,6 +73,7 @@ module_param(device_id_scheme, bool, 0444);
 static int only_lcd = -1;
 module_param(only_lcd, int, 0444);
 
+static bool may_report_brightness_keys;
 static int register_count;
 static DEFINE_MUTEX(register_count_mutex);
 static DEFINE_MUTEX(video_list_lock);
@@ -1222,6 +1223,9 @@ acpi_video_bus_get_one_device(struct acpi_device *device,
 	acpi_video_device_bind(video, data);
 	acpi_video_device_find_cap(data);
 
+	if (data->cap._BCM && data->cap._BCL)
+		may_report_brightness_keys = true;
+
 	mutex_lock(&video->device_list_lock);
 	list_add_tail(&data->entry, &video->video_device_list);
 	mutex_unlock(&video->device_list_lock);
@@ -1689,6 +1693,9 @@ static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data)
 		break;
 	}
 
+	if (keycode)
+		may_report_brightness_keys = true;
+
 	acpi_notifier_call_chain(device, event, 0);
 
 	if (keycode && (report_key_events & REPORT_BRIGHTNESS_KEY_EVENTS)) {
@@ -2249,6 +2256,7 @@ void acpi_video_unregister(void)
 	if (register_count) {
 		acpi_bus_unregister_driver(&acpi_video_bus);
 		register_count = 0;
+		may_report_brightness_keys = false;
 	}
 	mutex_unlock(&register_count_mutex);
 }
@@ -2270,13 +2278,7 @@ void acpi_video_unregister_backlight(void)
 
 bool acpi_video_handles_brightness_key_presses(void)
 {
-	bool have_video_busses;
-
-	mutex_lock(&video_list_lock);
-	have_video_busses = !list_empty(&video_bus_head);
-	mutex_unlock(&video_list_lock);
-
-	return have_video_busses &&
+	return may_report_brightness_keys &&
 	       (report_key_events & REPORT_BRIGHTNESS_KEY_EVENTS);
 }
 EXPORT_SYMBOL(acpi_video_handles_brightness_key_presses);
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 86fa61a21826..e2db1bdd9dd2 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -298,7 +298,7 @@ EXPORT_SYMBOL_GPL(osc_cpc_flexible_adr_space_confirmed);
 bool osc_sb_native_usb4_support_confirmed;
 EXPORT_SYMBOL_GPL(osc_sb_native_usb4_support_confirmed);
 
-bool osc_sb_cppc_not_supported;
+bool osc_sb_cppc2_support_acked;
 
 static u8 sb_uuid_str[] = "0811B06E-4A27-44F9-8D60-3CBBC22E7B48";
 static void acpi_bus_osc_negotiate_platform_control(void)
@@ -358,11 +358,6 @@ static void acpi_bus_osc_negotiate_platform_control(void)
 		return;
 	}
 
-#ifdef CONFIG_ACPI_CPPC_LIB
-	osc_sb_cppc_not_supported = !(capbuf_ret[OSC_SUPPORT_DWORD] &
-			(OSC_SB_CPC_SUPPORT | OSC_SB_CPCV2_SUPPORT));
-#endif
-
 	/*
 	 * Now run _OSC again with query flag clear and with the caps
 	 * supported by both the OS and the platform.
@@ -376,6 +371,10 @@ static void acpi_bus_osc_negotiate_platform_control(void)
 
 	capbuf_ret = context.ret.pointer;
 	if (context.ret.length > OSC_SUPPORT_DWORD) {
+#ifdef CONFIG_ACPI_CPPC_LIB
+		osc_sb_cppc2_support_acked = capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_CPCV2_SUPPORT;
+#endif
+
 		osc_sb_apei_support_acked =
 			capbuf_ret[OSC_SUPPORT_DWORD] & OSC_SB_APEI_SUPPORT;
 		osc_pc_lpi_support_confirmed =
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
index 903528f7e187..6ff1901d7d43 100644
--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -578,6 +578,19 @@ bool __weak cpc_ffh_supported(void)
 }
 
 /**
+ * cpc_supported_by_cpu() - check if CPPC is supported by CPU
+ *
+ * Check if the architectural support for CPPC is present even
+ * if the _OSC hasn't prescribed it
+ *
+ * Return: true for supported, false for not supported
+ */
+bool __weak cpc_supported_by_cpu(void)
+{
+	return false;
+}
+
+/**
  * pcc_data_alloc() - Allocate the pcc_data memory for pcc subspace
  *
  * Check and allocate the cppc_pcc_data memory.
@@ -684,8 +697,11 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
 	acpi_status status;
 	int ret = -ENODATA;
 
-	if (osc_sb_cppc_not_supported)
-		return -ENODEV;
+	if (!osc_sb_cppc2_support_acked) {
+		pr_debug("CPPC v2 _OSC not acked\n");
+		if (!cpc_supported_by_cpu())
+			return -ENODEV;
+	}
 
 	/* Parse the ACPI _CPC table for this CPU. */
 	status = acpi_evaluate_object_typed(handle, "_CPC", NULL, &output,