gpio: reduce the functionality of validate_desc()

Checking desc->gdev->chip for NULL without holding it in place with some
serializing mechanism is pointless. Remove this check. Also don't check
desc->gdev for NULL as it can never happen. We'll be protecting
gdev->chip with SRCU soon but we will provide a dedicated, automatic
class for that.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/gpio/gpiolib.c

@@ -2257,19 +2257,12 @@ static int validate_desc(const struct gpio_desc *desc, const char *func)
 {
 	if (!desc)
 		return 0;
+
 	if (IS_ERR(desc)) {
 		pr_warn("%s: invalid GPIO (errorpointer)\n", func);
 		return PTR_ERR(desc);
 	}
-	if (!desc->gdev) {
-		pr_warn("%s: invalid GPIO (no device)\n", func);
-		return -EINVAL;
-	}
-	if (!desc->gdev->chip) {
-		dev_warn(&desc->gdev->dev,
-			 "%s: backing chip is gone\n", func);
-		return 0;
-	}
+
 	return 1;
 }
 
@@ -2345,12 +2338,7 @@ static bool gpiod_free_commit(struct gpio_desc *desc)
 
 void gpiod_free(struct gpio_desc *desc)
 {
-	/*
-	 * We must not use VALIDATE_DESC_VOID() as the underlying gdev->chip
-	 * may already be NULL but we still want to put the references.
-	 */
-	if (!desc)
-		return;
+	VALIDATE_DESC_VOID(desc);
 
 	if (!gpiod_free_commit(desc))
 		WARN_ON(1);