[PATCH v1] soc/tegra: regulators: Fix locking up when voltage-spread is out of range

[PATCH v1] soc/tegra: regulators: Fix locking up when voltage-spread is out of range

[Dmitry Osipenko]

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@vger.kernel.org
Reported-by: Peter Geis <pgwipeout@gmail.com>
Tested-by: Peter Geis <pgwipeout@gmail.com> # Ouya T30
Tested-by: Matt Merhar <mattmerhar@protonmail.com> # Ouya T30
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/soc/tegra/regulators-tegra30.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/soc/tegra/regulators-tegra30.c b/drivers/soc/tegra/regulators-tegra30.c
index 7f21f31de09d..0e776b20f625 100644
--- a/drivers/soc/tegra/regulators-tegra30.c
+++ b/drivers/soc/tegra/regulators-tegra30.c
@@ -178,7 +178,7 @@ static int tegra30_voltage_update(struct tegra_regulator_coupler *tegra,
 	 * 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
-- 
2.29.2

Re: [PATCH v1] soc/tegra: regulators: Fix locking up when voltage-spread is out of range

[Thierry Reding]

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On Tue, Mar 02, 2021 at 04:18:00PM +0300, Dmitry Osipenko wrote:
> 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@vger.kernel.org
> Reported-by: Peter Geis <pgwipeout@gmail.com>
> Tested-by: Peter Geis <pgwipeout@gmail.com> # Ouya T30
> Tested-by: Matt Merhar <mattmerhar@protonmail.com> # Ouya T30
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/soc/tegra/regulators-tegra30.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Applied, thanks.

Thierry

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