From: Priit Laes <plaes@plaes.org>
To: Lee Jones <lee.jones@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>, Chen-Yu Tsai <wens@csie.org>,
Maxime Ripard <maxime.ripard@bootlin.com>,
Liam Girdwood <lgirdwood@gmail.com>,
Mark Brown <broonie@kernel.org>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Olliver Schinagl <oliver@schinagl.nl>,
linux-sunxi <linux-sunxi@googlegroups.com>
Cc: Priit Laes <plaes@plaes.org>
Subject: [PATCH v2 5/8] dt-bindings: mfd: axp20x: Add software based soft_start for AXP209 LDO3
Date: Tue, 11 Dec 2018 17:17:09 +0200 [thread overview]
Message-ID: <25e67fe9b5397aa5f11bdd7026e4ae6be51dd18b.1544512919.git-series.plaes@plaes.org> (raw)
In-Reply-To: <cover.923997dd7d7396bb4d71f8967698b58ca956b929.1544512919.git-series.plaes@plaes.org>
From: Olliver Schinagl <oliver@schinagl.nl>
In the past, there have been words on various lists that if LDO3 is
disabled in u-boot, but enabled in the DTS, the axp209 driver would
fail to continue/hang. Several enable/disable patches have been
issues to devicetree's in both the kernel and u-boot to address
this issue.
What really happened however, was that the AXP209 shuts down without
a notice and without setting an interrupt. This is caused when LDO3
gets overloaded, for example with large capacitors on the LDO3 output.
Normally, we would expect that AXP209 would source 200 mA as per
datasheet and set and trigger an interrupt when being overloaded.
For some reason however, this does not happen.
As a work-around, implement software-based 'regulator-soft-start'
property for AXP209 LDO3 regulator, which is used to first bring up
the LDO3 to the lowest possible voltage and then enable the LDO.
After that, we can set the requested voltage as usual.
Combining this setting with the regulator-ramp-delay allows LDO3 to
come up slowly and staggered, potentially reducing overall inrush current.
Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>
Signed-off-by: Priit Laes <plaes@plaes.org>
---
Documentation/devicetree/bindings/mfd/axp20x.txt | 3 +++
1 file changed, 3 insertions(+)
diff --git a/Documentation/devicetree/bindings/mfd/axp20x.txt b/Documentation/devicetree/bindings/mfd/axp20x.txt
index c626605..2af4ff9 100644
--- a/Documentation/devicetree/bindings/mfd/axp20x.txt
+++ b/Documentation/devicetree/bindings/mfd/axp20x.txt
@@ -37,6 +37,9 @@ more information:
- regulator-ramp-delay: sets the ramp up delay in uV/us
AXP20x/DCDC2: 1600, 800
AXP20x/LDO3: 1600, 800
+- regulator-soft-start: enable the output at the lowest possible voltage and
+ only then set the desired voltage
+ AXP20x/LDO3: software-based implementation
Optional properties:
- x-powers,dcdc-freq: defines the work frequency of DC-DC in KHz
--
git-series 0.9.1
next prev parent reply other threads:[~2018-12-11 15:17 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-11 15:17 [PATCH v2 0/8] regulator: axp20x: Stop AXP209 from crashing when enabling LDO3 Priit Laes
2018-12-11 15:17 ` [PATCH v2 1/8] mfd: axp20x: name voltage ramping define properly Priit Laes
2018-12-21 8:39 ` Lee Jones
2018-12-21 8:42 ` [linux-sunxi] " Priit Laes
2018-12-21 9:26 ` Lee Jones
2018-12-21 9:28 ` Priit Laes
2018-12-21 9:57 ` Lee Jones
2018-12-11 15:17 ` [PATCH v2 2/8] regulator: axp20x: add support for set_ramp_delay for AXP209 Priit Laes
2018-12-11 15:17 ` [PATCH v2 3/8] dt-bindings: mfd: axp20x: add support for regulator-ramp-delay " Priit Laes
2018-12-11 15:17 ` [PATCH v2 4/8] regulator: axp20x: add software based soft_start for AXP209 LDO3 Priit Laes
2018-12-11 15:17 ` Priit Laes [this message]
2018-12-21 8:40 ` [PATCH v2 5/8] dt-bindings: mfd: axp20x: Add " Lee Jones
2018-12-11 15:17 ` [PATCH v2 6/8] regulator: dts: enable soft-start and ramp delay for the OLinuXino Lime2 Priit Laes
2018-12-11 15:17 ` [PATCH v2 7/8] mfd: axp20x: Clean up included headers Priit Laes
2018-12-11 15:17 ` [PATCH v2 8/8] mfd: axp20x: use explicit bit defines Priit Laes
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