linux-kernel - [PATCH 3/3] regulator: resolve supply after creating regulator

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Message-Id: <ba09e0a8617ffeeb25cb4affffe6f3149319cef8.1601155770.git.mirq-linux@rere.qmqm.pl>
Date:   Sat, 26 Sep 2020 23:32:41 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jon Hunter <jonathanh@...dia.com>
Cc:     linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] regulator: resolve supply after creating regulator

When creating a new regulator its supply cannot create the sysfs link
because the device is not yet published. Remove early supply resolving
since it will be done later anyway. This makes the following error
disappear and the symlinks get created instead.

  DCDC_REG1: supplied by VSYS
  VSYS: could not add device link regulator.3 err -2

Note: It doesn't fix the problem for bypassed regulators, though.

Fixes: 45389c47526d ("regulator: core: Add early supply resolution for regulators")
Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
---
 drivers/regulator/core.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 6b56a22fd37f..607c2a76bb60 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -5279,15 +5279,20 @@ regulator_register(const struct regulator_desc *regulator_desc,
 	else if (regulator_desc->supply_name)
 		rdev->supply_name = regulator_desc->supply_name;
 
-	/*
-	 * Attempt to resolve the regulator supply, if specified,
-	 * but don't return an error if we fail because we will try
-	 * to resolve it again later as more regulators are added.
-	 */
-	if (regulator_resolve_supply(rdev))
-		rdev_dbg(rdev, "unable to resolve supply\n");
-
 	ret = set_machine_constraints(rdev, constraints);
+	if (ret == -EPROBE_DEFER) {
+		/* Regulator might be in bypass mode and so needs its supply
+		 * to set the constraints */
+		/* FIXME: this currently triggers a chicken-and-egg problem
+		 * when creating -SUPPLY symlink in sysfs to a regulator
+		 * that is just being created */
+		ret = regulator_resolve_supply(rdev);
+		if (!ret)
+			ret = set_machine_constraints(rdev, constraints);
+		else
+			rdev_dbg(rdev, "unable to resolve supply early: %pe\n",
+				 ERR_PTR(ret));
+	}
 	if (ret < 0)
 		goto wash;
 
-- 
2.20.1