[SRU][J][PATCH 11/12] gpio: aggregator: cancel deferred probe for devices created via configfs

[Koichiro Den]

BugLink: https://bugs.launchpad.net/bugs/2103496

For aggregators initialized via configfs, write 1 to 'live' waits for
probe completion and returns an error if the probe fails, unlike the
legacy sysfs interface, which is asynchronous.

Since users control the liveness of the aggregator device and might be
editing configurations while 'live' is 0, deferred probing is both
unnatural and unsafe.

Cancel deferred probe for purely configfs-based aggregators when probe
fails.

Signed-off-by: Koichiro Den <koichiro.den at canonical.com>
Link: https://lore.kernel.org/r/20250407043019.4105613-8-koichiro.den@canonical.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski at linaro.org>
(cherry picked from commit 0269c768de1b5e430c3f9a6869261606c82abe90 linux-next)
Signed-off-by: Koichiro Den <koichiro.den at canonical.com>
---
 drivers/gpio/gpio-aggregator.c | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-aggregator.c b/drivers/gpio/gpio-aggregator.c
index f23afa06a7f3..f578ac1312e8 100644
--- a/drivers/gpio/gpio-aggregator.c
+++ b/drivers/gpio/gpio-aggregator.c
@@ -69,6 +69,10 @@ struct gpio_aggregator_line {
 	enum gpio_lookup_flags flags;
 };
 
+struct gpio_aggregator_pdev_meta {
+	bool init_via_sysfs;
+};
+
 static DEFINE_MUTEX(gpio_aggregator_lock);	/* protects idr */
 static DEFINE_IDR(gpio_aggregator_idr);
 
@@ -1069,6 +1073,7 @@ static int gpio_aggregator_parse(struct gpio_aggregator *aggr)
 static ssize_t gpio_aggregator_new_device_store(struct device_driver *driver,
 						const char *buf, size_t count)
 {
+	struct gpio_aggregator_pdev_meta meta = { .init_via_sysfs = true };
 	char name[CONFIGFS_ITEM_NAME_LEN];
 	struct gpio_aggregator *aggr;
 	struct platform_device *pdev;
@@ -1119,7 +1124,7 @@ static ssize_t gpio_aggregator_new_device_store(struct device_driver *driver,
 
 	gpiod_add_lookup_table(aggr->lookups);
 
-	pdev = platform_device_register_simple(DRV_NAME, aggr->id, NULL, 0);
+	pdev = platform_device_register_data(NULL, DRV_NAME, aggr->id, &meta, sizeof(meta));
 	if (IS_ERR(pdev)) {
 		res = PTR_ERR(pdev);
 		goto remove_table;
@@ -1212,7 +1217,9 @@ ATTRIBUTE_GROUPS(gpio_aggregator);
 
 static int gpio_aggregator_probe(struct platform_device *pdev)
 {
+	struct gpio_aggregator_pdev_meta *meta;
 	struct device *dev = &pdev->dev;
+	bool init_via_sysfs = false;
 	struct gpio_desc **descs;
 	struct gpiochip_fwd *fwd;
 	int i, n;
@@ -1225,10 +1232,28 @@ static int gpio_aggregator_probe(struct platform_device *pdev)
 	if (!descs)
 		return -ENOMEM;
 
+	meta = dev_get_platdata(&pdev->dev);
+	if (meta && meta->init_via_sysfs)
+		init_via_sysfs = true;
+
 	for (i = 0; i < n; i++) {
 		descs[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
-		if (IS_ERR(descs[i]))
+		if (IS_ERR(descs[i])) {
+			/*
+			 * Deferred probing is not suitable when the aggregator
+			 * is created via configfs. They should just retry later
+			 * whenever they like. For device creation via sysfs,
+			 * error is propagated without overriding for backward
+			 * compatibility. .prevent_deferred_probe is kept unset
+			 * for other cases.
+			 */
+			if (!init_via_sysfs && !dev_of_node(dev) &&
+			    descs[i] == ERR_PTR(-EPROBE_DEFER)) {
+				pr_warn("Deferred probe canceled for creation via configfs.\n");
+				return -ENODEV;
+			}
 			return PTR_ERR(descs[i]);
+		}
 	}
 
 	fwd = gpiochip_fwd_create(dev, n, descs);
-- 
2.45.2