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From:   Sebastian Reichel <sebastian.reichel@collabora.com>
To:     Heiko Stuebner <heiko@sntech.de>, Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Lee Jones <lee@kernel.org>
Cc:     Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Mark Brown <broonie@kernel.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Alessandro Zummo <a.zummo@towertech.it>,
        linux-rockchip@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Sebastian Reichel <sebastian.reichel@collabora.com>,
        kernel@collabora.com
Subject: [PATCH v8 13/14] regulator: rk808: revert to synchronous probing
Date:   Thu,  4 May 2023 19:36:17 +0200
Message-Id: <20230504173618.142075-14-sebastian.reichel@collabora.com>
In-Reply-To: <20230504173618.142075-1-sebastian.reichel@collabora.com>
References: <20230504173618.142075-1-sebastian.reichel@collabora.com>
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The rk808 driver registers a bunch of regulator devices in a loop.
If one of the later regulators fails to register (usually because
its input supply is not yet available) everything will be unrolled
(i.e. previously registered regulators will be unregistered). With
asynchronous registration there might already be consumers, though.
We do not have the necessary infrastructure to properly unregister
the consumer device, so this scenario should be avoided.

First checking all input supplies or disallowing usage of the regulators
until all are registered does not work, since there can be
self-references (e.g. DCDC channels providing the supply of LDOs).

The only sensible solution I found is registering the regulator devices
asynchronously, so that we do not have to unroll. Since this is a major
rework let's revert back to synchronous probing for now to fix the issue
at hand.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
---
 drivers/regulator/rk808-regulator.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/regulator/rk808-regulator.c b/drivers/regulator/rk808-regulator.c
index 71a1ca8b917e..5f14d6dd4593 100644
--- a/drivers/regulator/rk808-regulator.c
+++ b/drivers/regulator/rk808-regulator.c
@@ -1355,7 +1355,7 @@ static struct platform_driver rk808_regulator_driver = {
 	.probe = rk808_regulator_probe,
 	.driver = {
 		.name = "rk808-regulator",
-		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+		.probe_type = PROBE_FORCE_SYNCHRONOUS,
 	},
 };
 
-- 
2.39.2