FAILED: patch "[PATCH] regulator: defer probe when trying to get voltage from" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From cf1ad559a20d1930aa7b47a52f54e1f8718de301 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Miros=C5=82aw?= <[email protected]>
Date: Mon, 2 Nov 2020 22:27:27 +0100
Subject: [PATCH] regulator: defer probe when trying to get voltage from
unresolved supply
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regulator_get_voltage_rdev() is called in regulator probe() when applying machine constraints. The "fixed" commit exposed the problem that non-bypassed regulators can forward the request to its parent (like bypassed ones) supply. Return -EPROBE_DEFER when the supply is expected but not resolved yet.

index a4ffd71696da..a5ad553da8cd 100644
@@ -4165,6 +4165,8 @@ int regulator_get_voltage_rdev(struct regulator_dev *rdev)
 		ret = rdev->desc->fixed_uV;
 	} else if (rdev->supply) {
 		ret = regulator_get_voltage_rdev(rdev->supply->rdev);
+	} else if (rdev->supply_name) {
+		return -EPROBE_DEFER;
 	} else {
 		return -EINVAL;
 	}