[PATCH 3/4] usb: typec: ucsi: acpi: Evaluate _DSM exclusively

[Ali Ahmet Memiş]

On some Lenovo IdeaPad and Yoga models, the UCSI _DSM accesses the EC 25
times through helpers that take a shared AML mutex with a 1 s timeout
and return 0 when it times out, so UCSI commands fail under contention
with the battery and ideapad methods.

Evaluate the _DSM with acpi_evaluate_dsm_exclusive().

Link: https://bugzilla.kernel.org/show_bug.cgi?id=221065
Signed-off-by: Ali Ahmet Memiş <aliamemis@xxxxxxxxxxx>
---
 drivers/usb/typec/ucsi/ucsi_acpi.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/typec/ucsi/ucsi_acpi.c b/drivers/usb/typec/ucsi/ucsi_acpi.c
index 5697ccc24ec3..0b9aaf317d2b 100644
--- a/drivers/usb/typec/ucsi/ucsi_acpi.c
+++ b/drivers/usb/typec/ucsi/ucsi_acpi.c
@@ -30,8 +30,12 @@ static int ucsi_acpi_dsm(struct ucsi_acpi *ua, int func)
 {
 	union acpi_object *obj;
 
-	obj = acpi_evaluate_dsm(ACPI_HANDLE(ua->dev), &ua->guid, 1, func,
-				NULL);
+	/*
+	 * On some Lenovo laptops the _DSM times out on the AML mutex it
+	 * shares with the battery and platform methods.
+	 */
+	obj = acpi_evaluate_dsm_exclusive(ACPI_HANDLE(ua->dev), &ua->guid, 1,
+					  func, NULL);
 	if (!obj) {
 		dev_err(ua->dev, "%s: failed to evaluate _DSM %d\n",
 			__func__, func);
-- 
2.55.0