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From:   Aaron Ma <aaron.ma@canonical.com>
To:     aaron.ma@canonical.com, mapengyu@gmail.com, ibm-acpi@hmh.eng.br,
        dvhart@infradead.org, andy@infradead.org,
        ibm-acpi-devel@lists.sourceforge.net,
        platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2] platform/x86: thinkpad_acpi: re-initialize ACPI buffer size when reuse
Date:   Sat,  3 Oct 2020 01:09:16 +0800
Message-Id: <20201002170916.64328-1-aaron.ma@canonical.com>
In-Reply-To: <20200929082025.51446-1-aaron.ma@canonical.com>
References: <20200929082025.51446-1-aaron.ma@canonical.com>
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Evaluating ACPI _BCL could fail, then ACPI buffer size will be set to 0.
When reuse this ACPI buffer, AE_BUFFER_OVERFLOW will be triggered.

Re-initialize buffer size will make ACPI evaluate successfully.

Fixes: 46445b6b896fd ("thinkpad-acpi: fix handle locate for video and query of _BCL")
Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
---
 drivers/platform/x86/thinkpad_acpi.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 9c4df41687a3..477d63c49c04 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -6829,8 +6829,10 @@ static int __init tpacpi_query_bcl_levels(acpi_handle handle)
 	list_for_each_entry(child, &device->children, node) {
 		acpi_status status = acpi_evaluate_object(child->handle, "_BCL",
 							  NULL, &buffer);
-		if (ACPI_FAILURE(status))
+		if (ACPI_FAILURE(status)) {
+			buffer.length = ACPI_ALLOCATE_BUFFER;
 			continue;
+		}
 
 		obj = (union acpi_object *)buffer.pointer;
 		if (!obj || (obj->type != ACPI_TYPE_PACKAGE)) {
-- 
2.28.0