linux-kernel - [PATCH] pinctrl: devicetree: do not goto err when probing hogs in pinctrl_dt_to

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Message-ID: <20250116170009.2075544-1-valentin.caron@foss.st.com>
Date: Thu, 16 Jan 2025 18:00:09 +0100
From: Valentin Caron <valentin.caron@...s.st.com>
To: Linus Walleij <linus.walleij@...aro.org>
CC: <linux-gpio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Valentin
 Caron <valentin.caron@...s.st.com>
Subject: [PATCH] pinctrl: devicetree: do not goto err when probing hogs in pinctrl_dt_to_map

Cross case in pinctrl framework make impossible to an hogged pin and
another, not hogged, used within the same device-tree node. For example
with this simplified device-tree :

  &pinctrl {
    pinctrl_pin_1: pinctrl-pin-1 {
      pins = "dummy-pinctrl-pin";
    };
  };

  &rtc {
    pinctrl-names = "default"
    pinctrl-0 = <&pinctrl_pin_1 &rtc_pin_1>

    rtc_pin_1: rtc-pin-1 {
      pins = "dummy-rtc-pin";
    };
  };

"pinctrl_pin_1" configuration is never set. This produces this path in
the code:

  really_probe()
    pinctrl_bind_pins()
    | devm_pinctrl_get()
    |   pinctrl_get()
    |     create_pinctrl()
    |       pinctrl_dt_to_map()
    |         // Hog pin create an abort for all pins of the node
    |         ret = dt_to_map_one_config()
    |         | /* Do not defer probing of hogs (circular loop) */
    |         | if (np_pctldev == p->dev->of_node)
    |         |   return -ENODEV;
    |         if (ret)
    |           goto err
    |
    call_driver_probe()
      stm32_rtc_probe()
        pinctrl_enable()
          pinctrl_claim_hogs()
            create_pinctrl()
              for_each_maps(maps_node, i, map)
                // Not hog pin is skipped
                if (pctldev && strcmp(dev_name(pctldev->dev),
                                      map->ctrl_dev_name))
                  continue;

At the first call of create_pinctrl() the hogged pin produces an abort to
avoid a defer of hogged pins. All other pin configurations are trashed.

At the second call, create_pinctrl is now called with pctldev parameter to
get hogs, but in this context only hogs are set. And other pins are
skipped.

To handle this, do not produce an abort in the first call of
create_pinctrl(). Classic pin configuration will be set in
pinctrl_bind_pins() context. And the hogged pin configuration will be set
in pinctrl_claim_hogs() context.

Signed-off-by: Valentin Caron <valentin.caron@...s.st.com>
---
 drivers/pinctrl/devicetree.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/pinctrl/devicetree.c b/drivers/pinctrl/devicetree.c
index 6a94ecd6a8de..0b7f74beb6a6 100644
--- a/drivers/pinctrl/devicetree.c
+++ b/drivers/pinctrl/devicetree.c
@@ -143,10 +143,14 @@ static int dt_to_map_one_config(struct pinctrl *p,
 		pctldev = get_pinctrl_dev_from_of_node(np_pctldev);
 		if (pctldev)
 			break;
-		/* Do not defer probing of hogs (circular loop) */
+		/*
+		 * Do not defer probing of hogs (circular loop)
+		 *
+		 * Return 1 to let the caller catch the case.
+		 */
 		if (np_pctldev == p->dev->of_node) {
 			of_node_put(np_pctldev);
-			return -ENODEV;
+			return 1;
 		}
 	}
 	of_node_put(np_pctldev);
@@ -265,6 +269,8 @@ int pinctrl_dt_to_map(struct pinctrl *p, struct pinctrl_dev *pctldev)
 			ret = dt_to_map_one_config(p, pctldev, statename,
 						   np_config);
 			of_node_put(np_config);
+			if (ret == 1)
+				continue;
 			if (ret < 0)
 				goto err;
 		}
-- 
2.25.1