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From:   Ivan Hu <ivan.hu@canonical.com>
To:     robert.moore@intel.com, rafael.j.wysocki@intel.com,
        lenb@kernel.org, linux-acpi@vger.kernel.org,
        acpica-devel@lists.linuxfoundation.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] ACPI: thermal: extend the acpi maximum handles for _PSL method
Date:   Wed,  9 Aug 2023 17:44:51 +0800
Message-Id: <20230809094451.15473-1-ivan.hu@canonical.com>
MIME-Version: 1.0
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Precedence: bulk

Several platforms encountered the following kernel message:
ACPI: \_TZ_.BATZ: Invalid passive threshold

This issue arises due to the failure of the acpi_evaluate_reference function
in drivers/acpi/thermal.c while evaluating the ACPI _PSL method.

status = acpi_evaluate_reference(tz->device->handle, "_PSL",
			 NULL, &devices);
if (ACPI_FAILURE(status)) {
	acpi_handle_info(tz->device->handle,
			 "Invalid passive threshold\n");
	tz->trips.passive.valid = false;
} else {
	tz->trips.passive.valid = true;
}

However, the root cause lies in the _PSL method returning packages with a count
exceeding ACPI_MAX_HANDLES in acpi_evaluate_reference.

As per the ACPI specification, the _PSL (Passive List) method is defined under
a thermal zone and evaluates to a list of processor objects to be used for
passive cooling. And it will return a variable-length Package containing a list
of References to processor objects.

Signed-off-by: Ivan Hu <ivan.hu@canonical.com>
---
 include/acpi/acpi_bus.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index 23fbe4a16972..dc7b38826113 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -13,7 +13,7 @@
 #include <linux/property.h>
 
 /* TBD: Make dynamic */
-#define ACPI_MAX_HANDLES	10
+#define ACPI_MAX_HANDLES	32
 struct acpi_handle_list {
 	u32 count;
 	acpi_handle handles[ACPI_MAX_HANDLES];
-- 
2.34.1