ACPI: processor: Print more information when acpi_processor_evaluate_cst() fails

Some platforms have bogus _CST which might cause unexpectd behavior
in the CPU idle driver. Some bogus _CST might be unable to be
disassembled by acpica-tools due to broken format.

Print extra log if the _CST extraction/verification failes.

This can be used to help narrow down why the CPU idle driver fails
to behave as expected.
Suggested-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_processor.c

@@ -798,22 +798,34 @@ int acpi_processor_evaluate_cst(acpi_handle handle, u32 cpu,
 		memset(&cx, 0, sizeof(cx));
 
 		element = &cst->package.elements[i];
-		if (element->type != ACPI_TYPE_PACKAGE)
+		if (element->type != ACPI_TYPE_PACKAGE) {
+			acpi_handle_info(handle, "_CST C%d type(%x) is not package, skip...\n",
+					 i, element->type);
 			continue;
+		}
 
-		if (element->package.count != 4)
+		if (element->package.count != 4) {
+			acpi_handle_info(handle, "_CST C%d package count(%d) is not 4, skip...\n",
+					 i, element->package.count);
 			continue;
+		}
 
 		obj = &element->package.elements[0];
 
-		if (obj->type != ACPI_TYPE_BUFFER)
+		if (obj->type != ACPI_TYPE_BUFFER) {
+			acpi_handle_info(handle, "_CST C%d package element[0] type(%x) is not buffer, skip...\n",
+					 i, obj->type);
 			continue;
+		}
 
 		reg = (struct acpi_power_register *)obj->buffer.pointer;
 
 		obj = &element->package.elements[1];
-		if (obj->type != ACPI_TYPE_INTEGER)
+		if (obj->type != ACPI_TYPE_INTEGER) {
+			acpi_handle_info(handle, "_CST C[%d] package element[1] type(%x) is not integer, skip...\n",
+					 i, obj->type);
 			continue;
+		}
 
 		cx.type = obj->integer.value;
 		/*
@@ -850,6 +862,8 @@ int acpi_processor_evaluate_cst(acpi_handle handle, u32 cpu,
 				cx.entry_method = ACPI_CSTATE_HALT;
 				snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT");
 			} else {
+				acpi_handle_info(handle, "_CST C%d declares FIXED_HARDWARE C-state but not supported in hardware, skip...\n",
+						 i);
 				continue;
 			}
 		} else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
@@ -857,6 +871,8 @@ int acpi_processor_evaluate_cst(acpi_handle handle, u32 cpu,
 			snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI IOPORT 0x%x",
 				 cx.address);
 		} else {
+			acpi_handle_info(handle, "_CST C%d space_id(%x) neither FIXED_HARDWARE nor SYSTEM_IO, skip...\n",
+					 i, reg->space_id);
 			continue;
 		}
 
@@ -864,14 +880,20 @@ int acpi_processor_evaluate_cst(acpi_handle handle, u32 cpu,
 			cx.valid = 1;
 
 		obj = &element->package.elements[2];
-		if (obj->type != ACPI_TYPE_INTEGER)
+		if (obj->type != ACPI_TYPE_INTEGER) {
+			acpi_handle_info(handle, "_CST C%d package element[2] type(%x) not integer, skip...\n",
+					 i, obj->type);
 			continue;
+		}
 
 		cx.latency = obj->integer.value;
 
 		obj = &element->package.elements[3];
-		if (obj->type != ACPI_TYPE_INTEGER)
+		if (obj->type != ACPI_TYPE_INTEGER) {
+			acpi_handle_info(handle, "_CST C%d package element[3] type(%x) not integer, skip...\n",
+					 i, obj->type);
 			continue;
+		}
 
 		memcpy(&info->states[++last_index], &cx, sizeof(cx));
 	}