[PATCH AUTOSEL 6.18-5.10] gpiolib: acpi: Fix gpio count with string references

[Sasha Levin <sashal@kernel.org>]

From: Alban Bedel <alban.bedel@lht.dlh.de>

[ Upstream commit c62e0658d458d8f100445445c3ddb106f3824a45 ]

Since commit 9880702d123f2 ("ACPI: property: Support using strings in
reference properties") it is possible to use strings instead of local
references. This work fine with single GPIO but not with arrays as
acpi_gpio_package_count() didn't handle this case. Update it to handle
strings like local references to cover this case as well.

Signed-off-by: Alban Bedel <alban.bedel@lht.dlh.de>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://patch.msgid.link/20260129145944.3372777-1-alban.bedel@lht.dlh.de
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

The prerequisite commit appeared in v6.10+. So the bug affects stable
trees from 6.10 onward (6.10.y, 6.11.y, 6.12.y, etc.).

### 7. CONCLUSION

This commit:
- **Fixes a real bug**: GPIO array counting fails when ACPI firmware
  uses string references
- **Is obviously correct**: Adding a switch case for strings to match
  the same handling as local references
- **Is minimal**: One line addition
- **Has zero risk**: Cannot affect existing code paths; only enables a
  new case in a switch statement
- **Has been reviewed** by the ACPI/GPIO maintainer (Mika Westerberg)
  and merged by the GPIO maintainer (Bartosz Golaszewski)
- **Has a clear dependency**: Only applies to trees with commit
  `9880702d123f2` (v6.10+)
- **Fixes real hardware support**: Users with firmware using string
  references for GPIO arrays would have broken device functionality

This is a textbook stable backport candidate: small, surgical, correct,
and fixes real user-impacting functionality.

**YES**

 drivers/gpio/gpiolib-acpi-core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpio/gpiolib-acpi-core.c b/drivers/gpio/gpiolib-acpi-core.c
index e64e21fd6bbaa..8110690ea69d0 100644
--- a/drivers/gpio/gpiolib-acpi-core.c
+++ b/drivers/gpio/gpiolib-acpi-core.c
@@ -1359,6 +1359,7 @@ static int acpi_gpio_package_count(const union acpi_object *obj)
 	while (element < end) {
 		switch (element->type) {
 		case ACPI_TYPE_LOCAL_REFERENCE:
+		case ACPI_TYPE_STRING:
 			element += 3;
 			fallthrough;
 		case ACPI_TYPE_INTEGER:
-- 
2.51.0