[PATCH v2] gpio: grgpio: Fix device removing

[Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>]

If a platform device's remove callback returns non-zero, the device core
emits a warning and still removes the device and calls the devm cleanup
callbacks.

So it's not save to not unregister the gpiochip because on the next request
to a GPIO the driver accesses kfree()'d memory. Also if an IRQ triggers,
the freed memory is accessed.

Instead rely on the GPIO framework to ensure that after gpiochip_remove()
all GPIOs are freed and so the corresponding IRQs are unmapped.

This is a preparation for making platform remove callbacks return void.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
---
Changes since (implicit) v1
(Message-Id: 20220620122933.106035-1-u.kleine-koenig@xxxxxxxxxxxxxx):

 - Fix capitalisation of GPIO and IRQ in commit log
 - Add another "are" in the third paragraph.
 - Drop note about a potential bug in GPIO framework
   I'm not sure there is actually a bug.

Thanks to Andy Shevchenko for his feedback.

Best regards
Uwe

 drivers/gpio/gpio-grgpio.c | 14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

diff --git a/drivers/gpio/gpio-grgpio.c b/drivers/gpio/gpio-grgpio.c
index df563616f943..bea0e32c195d 100644
--- a/drivers/gpio/gpio-grgpio.c
+++ b/drivers/gpio/gpio-grgpio.c
@@ -434,25 +434,13 @@ static int grgpio_probe(struct platform_device *ofdev)
 static int grgpio_remove(struct platform_device *ofdev)
 {
 	struct grgpio_priv *priv = platform_get_drvdata(ofdev);
-	int i;
-	int ret = 0;
-
-	if (priv->domain) {
-		for (i = 0; i < GRGPIO_MAX_NGPIO; i++) {
-			if (priv->uirqs[i].refcnt != 0) {
-				ret = -EBUSY;
-				goto out;
-			}
-		}
-	}
 
 	gpiochip_remove(&priv->gc);
 
 	if (priv->domain)
 		irq_domain_remove(priv->domain);
 
-out:
-	return ret;
+	return 0;
 }
 
 static const struct of_device_id grgpio_match[] = {

base-commit: f2906aa863381afb0015a9eb7fefad885d4e5a56
-- 
2.36.1