From: Surendra Singh Chouhan <kr494167@gmail.com>

PALC_DSM_FN_TRIGGER_PLDR was defined as BIT(1) (value 2).

acpi_evaluate_dsm() expects a 0-based function index integer (0, 1,
2, ...), whereas acpi_check_dsm() expects a bitmask of supported
function indices (BIT(1), BIT(2), ...).

Because PALC_DSM_FN_TRIGGER_PLDR was defined as BIT(1),
acpi_evaluate_dsm() was evaluating Function Index 2 instead of Function
Index 1, while acpi_check_dsm() was checking for Function Index 1
support.

Fix this by setting PALC_DSM_FN_TRIGGER_PLDR to 1 (the function index)
and passing BIT(PALC_DSM_FN_TRIGGER_PLDR) to acpi_check_dsm().

Fixes: 1ab843135a77 ("platform/x86: dell-dw5826e: Add reset driver for DW5826e")
Signed-off-by: Surendra Singh Chouhan <kr494167@gmail.com>
---
v2:
 - Use full name "Surendra Singh Chouhan" in From header and Signed-off-by.

 drivers/platform/x86/dell/dell-dw5826e-reset.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/platform/x86/dell/dell-dw5826e-reset.c b/drivers/platform/x86/dell/dell-dw5826e-reset.c
index 1ca7c3421bb5..64e6e9b1d7a0 100644
--- a/drivers/platform/x86/dell/dell-dw5826e-reset.c
+++ b/drivers/platform/x86/dell/dell-dw5826e-reset.c
@@ -13,7 +13,7 @@
 #include <linux/types.h>
 #include <linux/uuid.h>
 
-#define PALC_DSM_FN_TRIGGER_PLDR    BIT(1)
+#define PALC_DSM_FN_TRIGGER_PLDR    1
 
 static guid_t palc_dsm_guid =
 	GUID_INIT(0x5a1a4bba, 0x8006, 0x487e, 0xbe, 0x0a, 0xac, 0xf5, 0xd8, 0xfd, 0xfe, 0x59);
@@ -66,7 +66,7 @@ static int palc_probe(struct platform_device *pdev)
 	if (!handle)
 		return -ENODEV;
 
-	if (!acpi_check_dsm(handle, &palc_dsm_guid, 1, PALC_DSM_FN_TRIGGER_PLDR))
+	if (!acpi_check_dsm(handle, &palc_dsm_guid, 1, BIT(PALC_DSM_FN_TRIGGER_PLDR)))
 		return -ENODEV;
 
 	return 0;
-- 
2.55.0

On Fri, 24 Jul 2026 18:25:33 +0530, kr494167@gmail.com wrote:

> PALC_DSM_FN_TRIGGER_PLDR was defined as BIT(1) (value 2).
> 
> acpi_evaluate_dsm() expects a 0-based function index integer (0, 1,
> 2, ...), whereas acpi_check_dsm() expects a bitmask of supported
> function indices (BIT(1), BIT(2), ...).
> 
> Because PALC_DSM_FN_TRIGGER_PLDR was defined as BIT(1),
> acpi_evaluate_dsm() was evaluating Function Index 2 instead of Function
> Index 1, while acpi_check_dsm() was checking for Function Index 1
> support.
> 
> [...]


Thank you for your contribution, it has been applied to my local
review-ilpo-fixes branch. Note it will show up in the public
platform-drivers-x86/review-ilpo-fixes branch only once I've pushed my
local branch there, which might take a while.

The list of commits applied:
[1/1] platform/x86: dell-dw5826e: fix ACPI _DSM function index and bitmask usage
      commit: 39490ec6063d9dc3d995b7b48fc5106cd361a547

--
 i.