Subject: [PATCH] pinctrl: at91: fix deferred probing support

From: [email-masked] (Rob Herring)
Date: Thu, 12 Jul 2018 13:22:22 -0600

AT91 pinctrl deferred probing support is broken if the GPIO devices
haven't probed first and set gpio_banks to non-zero. The later condition
that only some GPIO devices haven't probed can't actually happen as
either all the GPIO devices have probed first or none of them have. Plus
the pinctrl driver has already returned -EINVAL, so it's not on the
deferred list to retry probing.

Fix this by consolidating the checking that all GPIO devices are probed.

Cc: Jean-Christophe Plagniol-Villard <[email-masked]>
Cc: Linus Walleij <[email-masked]>
Cc: Nicolas Ferre <[email-masked]>
Cc: Alexandre Belloni <[email-masked]>
Cc: linux-arm-kernel at lists.infradead.org
Cc: linux-gpio at vger.kernel.org
Signed-off-by: Rob Herring <[email-masked]>
---
This is a result of trying to remove of_platform_default_populate from 
at91 code and relying on the DT core handling populating devices. That 
changed the probe order and broke booting.

Compile tested only.

Rob

 drivers/pinctrl/pinctrl-at91.c | 36 ++++++++++++----------------------
 1 file changed, 13 insertions(+), 23 deletions(-)

diff --git a/drivers/pinctrl/pinctrl-at91.c b/drivers/pinctrl/pinctrl-at91.c
index 50f0ec42c637..167838901b75 100644
--- a/drivers/pinctrl/pinctrl-at91.c
+++ b/drivers/pinctrl/pinctrl-at91.c
@@ -1162,7 +1162,7 @@ static int at91_pinctrl_probe_dt(struct platform_device *pdev,
 				 struct at91_pinctrl *info)
 {
 	int ret = 0;
-	int i, j;
+	int i, j, ngpio_chips_enabled = 0;
 	uint32_t *tmp;
 	struct device_node *np = pdev->dev.of_node;
 	struct device_node *child;
@@ -1175,10 +1175,17 @@ static int at91_pinctrl_probe_dt(struct platform_device *pdev,
 		of_match_device(at91_pinctrl_of_match, &pdev->dev)->data;
 	at91_pinctrl_child_count(info, np);
 
-	if (gpio_banks < 1) {
-		dev_err(&pdev->dev, "you need to specify at least one gpio-controller\n");
-		return -EINVAL;
-	}
+	/*
+	 * We need all the GPIO drivers to probe FIRST, or we will not be able
+	 * to obtain references to the struct gpio_chip * for them, and we
+	 * need this to proceed.
+	 */
+	for (i = 0; i < MAX_GPIO_BANKS; i++)
+		if (gpio_chips[i])
+			ngpio_chips_enabled++;
+
+	if (ngpio_chips_enabled < info->nactive_banks)
+		return -EPROBE_DEFER;
 
 	ret = at91_pinctrl_mux_mask(info, np);
 	if (ret)
@@ -1234,7 +1241,7 @@ static int at91_pinctrl_probe(struct platform_device *pdev)
 {
 	struct at91_pinctrl *info;
 	struct pinctrl_pin_desc *pdesc;
-	int ret, i, j, k, ngpio_chips_enabled = 0;
+	int ret, i, j, k;
 
 	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
 	if (!info)
@@ -1244,23 +1251,6 @@ static int at91_pinctrl_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	/*
-	 * We need all the GPIO drivers to probe FIRST, or we will not be able
-	 * to obtain references to the struct gpio_chip * for them, and we
-	 * need this to proceed.
-	 */
-	for (i = 0; i < gpio_banks; i++)
-		if (gpio_chips[i])
-			ngpio_chips_enabled++;
-
-	if (ngpio_chips_enabled < info->nactive_banks) {
-		dev_warn(&pdev->dev,
-			 "All GPIO chips are not registered yet (%d/%d)\n",
-			 ngpio_chips_enabled, info->nactive_banks);
-		devm_kfree(&pdev->dev, info);
-		return -EPROBE_DEFER;
-	}
-
 	at91_pinctrl_desc.name = dev_name(&pdev->dev);
 	at91_pinctrl_desc.npins = gpio_banks * MAX_NB_GPIO_PER_BANK;
 	at91_pinctrl_desc.pins = pdesc =
-- 
2.17.1