linux-kernel - [PATCH 5.12 038/677] soc/tegra: regulators: Fix locking up when voltage-spread is out of range

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Message-Id: <20210512144838.477806971@linuxfoundation.org>
Date:   Wed, 12 May 2021 16:41:24 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Peter Geis <pgwipeout@...il.com>,
        Dmitry Osipenko <digetx@...il.com>,
        Thierry Reding <treding@...dia.com>,
        Matt Merhar <mattmerhar@...tonmail.com>
Subject: [PATCH 5.12 038/677] soc/tegra: regulators: Fix locking up when voltage-spread is out of range

From: Dmitry Osipenko <digetx@...il.com>

commit ef85bb582c41524e9e68dfdbde48e519dac4ab3d upstream.

Fix voltage coupler lockup which happens when voltage-spread is out
of range due to a bug in the code. The max-spread requirement shall be
accounted when CPU regulator doesn't have consumers. This problem is
observed on Tegra30 Ouya game console once system-wide DVFS is enabled
in a device-tree.

Fixes: 783807436f36 ("soc/tegra: regulators: Add regulators coupler for Tegra30")
Cc: stable@...r.kernel.org
Reported-by: Peter Geis <pgwipeout@...il.com>
Tested-by: Peter Geis <pgwipeout@...il.com> # Ouya T30
Tested-by: Matt Merhar <mattmerhar@...tonmail.com> # Ouya T30
Signed-off-by: Dmitry Osipenko <digetx@...il.com>
Signed-off-by: Thierry Reding <treding@...dia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/soc/tegra/regulators-tegra30.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/soc/tegra/regulators-tegra30.c
+++ b/drivers/soc/tegra/regulators-tegra30.c
@@ -178,7 +178,7 @@ static int tegra30_voltage_update(struct
 	 * survive the voltage drop if it's running on a higher frequency.
 	 */
 	if (!cpu_min_uV_consumers)
-		cpu_min_uV = cpu_uV;
+		cpu_min_uV = max(cpu_uV, cpu_min_uV);
 
 	/*
 	 * Bootloader shall set up voltages correctly, but if it