[PATCH v4 8/9] gpio: aggregator: cancel deferred probe for devices created via configfs

[Koichiro Den <koichiro.den@xxxxxxxxxxxxx>]

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@xxxxxxxxxxxxx>
---
 drivers/gpio/gpio-aggregator.c | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/gpio-aggregator.c b/drivers/gpio/gpio-aggregator.c
index 8f8793f27211..f6beb9f41b9a 100644
--- a/drivers/gpio/gpio-aggregator.c
+++ b/drivers/gpio/gpio-aggregator.c
@@ -72,6 +72,10 @@ 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);
 
@@ -1112,6 +1116,7 @@ static int aggr_parse(struct gpio_aggregator *aggr)
 static ssize_t 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;
@@ -1161,7 +1166,7 @@ static ssize_t new_device_store(struct device_driver *driver, const char *buf,
 
 	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;
@@ -1242,14 +1247,15 @@ static struct attribute *gpio_aggregator_attrs[] = {
 };
 ATTRIBUTE_GROUPS(gpio_aggregator);
 
-
 /*
  *  GPIO Aggregator platform device
  */
 
 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;
 	unsigned long features;
@@ -1263,10 +1269,28 @@ 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]);
+		}
 	}
 
 	features = (uintptr_t)device_get_match_data(dev);
-- 
2.45.2