arm64: tegra: Update Jetson TX1 GPU regulator timings [Linux 4.9.187]

This Linux kernel change "arm64: tegra: Update Jetson TX1 GPU regulator timings" is included in the Linux 4.9.187 release. This change is authored by Jon Hunter <jonathanh [at] nvidia.com> on Thu Jun 20 09:17:01 2019 +0100. The commit for this change in Linux stable tree is 79c0a0b (patch) which is from upstream commit ece6031. The same Linux upstream change may have been applied to various maintained Linux releases and you can find all Linux releases containing changes from upstream ece6031.

arm64: tegra: Update Jetson TX1 GPU regulator timings

commit ece6031ece2dd64d63708cfe1088016cee5b10c0 upstream.

The GPU regulator enable ramp delay for Jetson TX1 is set to 1ms which
not sufficient because the enable ramp delay has been measured to be
greater than 1ms. Furthermore, the downstream kernels released by NVIDIA
for Jetson TX1 are using a enable ramp delay 2ms and a settling delay of
160us. Update the GPU regulator enable ramp delay for Jetson TX1 to be
2ms and add a settling delay of 160us.

Cc: [email protected]
Signed-off-by: Jon Hunter <[email protected]>
Fixes: 5e6b9a89afce ("arm64: tegra: Add VDD_GPU regulator to Jetson TX1")
Signed-off-by: Thierry Reding <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

There are 3 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 arch/arm64/boot/dts/nvidia/tegra210-p2180.dtsi | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/nvidia/tegra210-p2180.dtsi b/arch/arm64/boot/dts/nvidia/tegra210-p2180.dtsi
index 906fb83..6a51d28 100644
--- a/arch/arm64/boot/dts/nvidia/tegra210-p2180.dtsi
+++ b/arch/arm64/boot/dts/nvidia/tegra210-p2180.dtsi
@@ -306,7 +306,8 @@
            regulator-max-microvolt = <1320000>;
            enable-gpios = <&pmic 6 GPIO_ACTIVE_HIGH>;
            regulator-ramp-delay = <80>;
-           regulator-enable-ramp-delay = <1000>;
+           regulator-enable-ramp-delay = <2000>;
+           regulator-settling-time-us = <160>;
        };
    };
 };

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