[PATCH 5/8] acpi: Check returned object type by Optimus _DSM locally

[Pierre Moreau]

Most _DSM will return an integer value of 0x80000002 when given an unknown
UUID, revision ID or function ID. Checking locally allows us to differentiate
that case from other ACPI errors, and to not report a "failed to evaluate _DSM"
if 0x80000002 is returned which was confusing.

Signed-off-by: Pierre Moreau <pierre.morrow at free.fr>
---
 drm/nouveau/nouveau_acpi.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drm/nouveau/nouveau_acpi.c b/drm/nouveau/nouveau_acpi.c
index 073f7d7..7aeaf7d 100644
--- a/drm/nouveau/nouveau_acpi.c
+++ b/drm/nouveau/nouveau_acpi.c
@@ -88,12 +88,12 @@ static int nouveau_evaluate_optimus_dsm(acpi_handle handle, int func, int arg, u
 	for (i = 0; i < 4; i++)
 		args_buff[i] = (arg >> i * 8) & 0xFF;
 
-	obj = acpi_evaluate_dsm_typed(handle, nouveau_op_dsm_muid, nouveau_op_dsm_rid,
-				      func, &argv4, ACPI_TYPE_BUFFER);
+	obj = acpi_evaluate_dsm(handle, nouveau_op_dsm_muid, nouveau_op_dsm_rid,
+			        func, &argv4);
 	if (!obj) {
 		acpi_handle_info(handle, "failed to evaluate _DSM\n");
 		return AE_ERROR;
-	} else {
+	} else if (obj->type == ACPI_TYPE_BUFFER) {
 		if (!result && obj->buffer.length == 4) {
 			*result  = obj->buffer.pointer[0];
 			*result |= (obj->buffer.pointer[1] << 8);
@@ -101,6 +101,15 @@ static int nouveau_evaluate_optimus_dsm(acpi_handle handle, int func, int arg, u
 			*result |= (obj->buffer.pointer[3] << 24);
 		}
 		ACPI_FREE(obj);
+	} else if (obj->type == ACPI_TYPE_INTEGER &&
+		   obj->integer.value == 0x80000002) {
+		acpi_handle_debug(handle, "failed to query Optimus _DSM\n");
+		ACPI_FREE(obj);
+		return -ENODEV;
+	} else {
+		acpi_handle_err(handle, "unexpected returned value by Optimus _DSM\n");
+		ACPI_FREE(obj);
+		return AE_ERROR;
 	}
 
 	return 0;
-- 
2.4.1