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Olliver Schinagl 77e3e3b165
regulator: axp20x: add software based soft_start for AXP209 LDO3
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, we use the soft-start constraint of the regulator
node 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
enable voltage slowly and staggered, potentially reducing overall
inrush current.

Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>
Signed-off-by: Priit Laes <plaes@plaes.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
2018-12-13 16:39:55 +00:00
arch Merge branch 'for-linus' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator into regulator-4.21 2018-12-11 20:44:49 +00:00
block blk-mq: punt failed direct issue to dispatch list 2018-12-07 08:16:11 -07:00
certs
crypto
Documentation dt-bindings: mfd: axp20x: add support for regulator-ramp-delay for AXP209 2018-12-13 16:39:54 +00:00
drivers regulator: axp20x: add software based soft_start for AXP209 LDO3 2018-12-13 16:39:55 +00:00
firmware
fs a fix for smb3 direct i/o, a fix for CIFS DFS for stable and a minor cifs Kconfig fix 2018-12-09 10:15:13 -08:00
include mfd: axp20x: name voltage ramping define properly 2018-12-13 16:39:46 +00:00
init
ipc
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-12-09 15:12:33 -08:00
lib
LICENSES
mm dax fixes 4.20-rc6 2018-12-09 09:54:04 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-12-09 15:12:33 -08:00
samples
scripts Fixes for stackleak 2018-12-07 13:13:07 -08:00
security
sound
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-12-09 15:12:33 -08:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS MAINTAINERS: add maintainer for MCP16502 PMIC driver 2018-12-13 12:18:56 +00:00
Makefile Linux 4.20-rc6 2018-12-09 15:31:00 -08:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.