[U-Boot] [PATCH v3 0/9] Stop AXP from crashing when enabling LDO3

[Priit Laes]

On Wed, Nov 21, 2018 at 08:05:24PM +0200, Priit Laes wrote:
> This is a resend/v2 of a "Stop AXP from crashing when enabling LDO3" series,
> posted by Olliver Schinagl in March 2017. Unfortunately it never got past
> initial discussion [1], but most Olimex Lime2 boards are still running
> into this bug.

Well, this is actually v3. Missed this paragraph when pushing out v3.

> When powering up an AXP209, the default value for LDO3 output is enabled. This
> works fine. However if for whatever reason, LDO3 is disabled, for example by OS
> during reboot and u-boot enables LDO3 again, the PMIC shuts down (without
> setting an interrupt) causing the board to hang. This behavior has been seen
> from Linux as well, u-boot disables LDO3 as a default value, the kernel enables
> it per its DTS, the kernel hangs as the PMIC gets shut down.
> 
> The root cause is that some boards have too high capacitance on the LDO3 output
> port causing inrush currents exceeding the maximum of the AXP209.
> 
> The fix is to turn on the LDO3 at the lowest possible voltage and then set the
> final voltage.
> 
> If the capacitance is really big (due to a connected device for example) the
> AXP209 also features VRC, or Voltage Rate Control, allowing voltage to ramp up
> even slower.
> 
> Similar changes need to be also implemented in the operating system driver
> side when driver needs to toggle power for the ALDO3 regulator.
> 
> This patch series implements the above with a few tiny cleanups.
> 
> The initial discussion with some scope screenshots can be found in the
> linux-sunxi mailing list [0].
> 
> And the initial series were posted to u-boot mailing list [1].
> 
> Signed-off-by: Olliver Schinagl <oliver at schinagl.nl>
> Signed-off-by: Priit Laes <plaes at plaes.org>
> 
> [0] https://groups.google.com/forum/m/#!topic/linux-sunxi/EDvEsbHHqQI
> [1] https://lists.denx.de/pipermail/u-boot/2017-March/282789.html
> 
> --
> Changes since v2:
> - Collected Acked-by tags, patches 1,3-5 are now ripe for picking.
> - Olliver fixed wrong code in patch 2, thanks for Maxime for spotting
> - Fixed checkpatch error in patch 5
> - Expanded commit message for patch 6
> 
> Changes from initial submission:
> - Rebased on top of latest master and fixed conflicts
> - Added comments about datasheet errors for patch 6
> - Fixed some typos and checkpatch errors
> - Added patch to Olimex Lime2 eMMC board
> 
> Olliver Schinagl (8):
>   sunxi: board: Print error after power initialization fails
>   sunxi: pmic_bus: Decrease boot time by not writing duplicate data
>   power: axp209: Use BIT() macro
>   power: axp209: Define the chip version mask
>   power: axp209: Reduce magic values by adding defines for LDO[234]
>   power: axp209: Add support for voltage rate control on LDO3
>   power: axp209: Limit inrush current for broken boards
>   arm: sunxi: Reduce inrush current on Olimex OLinuXino-A20-Lime2
> 
> Priit Laes (1):
>   arm: sunxi: Reduce inrush current on Olimex OLinuXino-A20-Lime2-eMMC
> 
>  arch/arm/mach-sunxi/pmic_bus.c             |  6 ++-
>  board/sunxi/board.c                        | 18 +++---
>  configs/A20-OLinuXino-Lime2-eMMC_defconfig |  2 +-
>  configs/A20-OLinuXino-Lime2_defconfig      |  2 +-
>  drivers/power/Kconfig                      | 43 ++++++++++++++-
>  drivers/power/axp209.c                     | 66 ++++++++++++++++++----
>  include/axp209.h                           | 70 +++++++++++++++++------
>  7 files changed, 172 insertions(+), 35 deletions(-)
> 
> base-commit: a3e1653ddeb02f39481eba572275016171e9670c
> -- 
> git-series 0.9.1