When the user of a shared GPIO managed by gpio-shared-proxy calls
gpiod_put() to release it, we never undo the potential "vote" for
driving the shared line "high". In the free() callback, check if this
proxy voted for "high" and - if so - decrease the number of votes and
potentially revert the value to low if this is the last user.

Cc: stable@vger.kernel.org
Fixes: e992d54c6f97 ("gpio: shared-proxy: implement the shared GPIO proxy driver")
Closes: https://sashiko.dev/#/patchset/20260513-gpio-shared-dynamic-voting-v1-1-8e1c49961b7d%40oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
---
Sashiko commented on this pre-existing issue under my patch changing the
voting heuristic.
---
Changes in v2:
- When releasing the shared GPIO, restore the value to the "default" low
  using the existing interface to keep track of the votes correctly
- Link to v1: https://patch.msgid.link/20260520-gpio-shared-free-vote-v1-1-6c54966583e2@oss.qualcomm.com
---
 drivers/gpio/gpio-shared-proxy.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpio/gpio-shared-proxy.c b/drivers/gpio/gpio-shared-proxy.c
index 29d7d2e4dfc02c34fb3f2abc343ee30b61579b66..c43a117de016af03282961ec843ffa8cea00ec5a 100644
--- a/drivers/gpio/gpio-shared-proxy.c
+++ b/drivers/gpio/gpio-shared-proxy.c
@@ -103,9 +103,17 @@ static void gpio_shared_proxy_free(struct gpio_chip *gc, unsigned int offset)
 {
 	struct gpio_shared_proxy_data *proxy = gpiochip_get_data(gc);
 	struct gpio_shared_desc *shared_desc = proxy->shared_desc;
+	int ret;
 
 	guard(gpio_shared_desc_lock)(shared_desc);
 
+	if (proxy->voted_high) {
+		ret = gpio_shared_proxy_set_unlocked(proxy, gpiod_set_value_cansleep, 0);
+		if (ret)
+			dev_err(proxy->dev,
+				"Failed to unset the shared GPIO value on release: %d\n", ret);
+	}
+
 	proxy->shared_desc->usecnt--;
 
 	dev_dbg(proxy->dev, "Shared GPIO freed, number of users: %u\n",

---
base-commit: 687da68900cd1a46549f7d9430c7d40346cb86a0
change-id: 20260520-gpio-shared-free-vote-f62333ab4fff

Best regards,
-- 
Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>