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Douglas Anderson 5584119905
regulator: core: Require regulator drivers to check uV for get_optimum_mode()
The get_optimum_mode() for regulator drivers is passed the input
voltage and output voltage as well as the current. This is because, in
theory, the optimum mode can depend on all three things.

It turns out that for all regulator drivers in mainline only the
current is looked at when implementing get_optimum_mode(). None of the
drivers take the input or output voltage into account. Despite the
fact that none of the drivers take the input or output voltage into
account, though, the regulator framework will error out before calling
into get_optimum_mode() if it doesn't know the input or output
voltage.

The above behavior turned out to be a probelm for some boards when we
landed commit efb0cb50c4 ("regulator: qcom-rpmh: Implement
get_optimum_mode(), not set_load()"). Before that change we'd have no
problems running drms_uA_update() for RPMH regulators even if a
regulator's input or output voltage was unknown. After that change
drms_uA_update() started to fail. This is because typically boards
using RPMH regulators don't model the input supplies of RPMH
regulators. Input supplies for RPMH regulators nearly always come from
the output of other RPMH regulators (or always-on regulators) and RPMH
firmware is initialized with this knowledge and handles enabling (and
adjusting the voltage of) input supplies. While we could model the
parent/child relationship of the regulators in Linux, many boards
don't bother since it adds extra overhead.

Let's change the regulator core to make things work again. Now if we
fail to get the input or output voltage we'll still call into
get_optimum_mode() and we'll just pass error codes in for input_uV
and/or output_uV parameters.

Since no existing regulator drivers even look at input_uV and
output_uV we don't need to add this error handling anywhere right
now. We'll add some comments in the core so that it's obvious that (if
regulator drivers care) it's up to them to add the checks.

Reported-by: Andrew Halaney <ahalaney@redhat.com>
Fixes: efb0cb50c4 ("regulator: qcom-rpmh: Implement get_optimum_mode(), not set_load()")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Andrew Halaney <ahalaney@redhat.com>
Link: https://lore.kernel.org/r/20220824142229.RFT.v2.1.I137e6bef4f6d517be7b081be926059321102fd3d@changeid
Signed-off-by: Mark Brown <broonie@kernel.org>
2022-08-25 17:58:32 +01:00
arch xen: branch for v6.0-rc1b 2022-08-14 09:28:54 -07:00
block block-6.0-2022-08-12 2022-08-13 13:37:36 -07:00
certs Kbuild updates for v5.20 2022-08-10 10:40:41 -07:00
crypto crypto: blake2b: effectively disable frame size warning 2022-08-10 17:59:11 -07:00
Documentation PM6125 regulator support 2022-08-23 22:14:44 +01:00
drivers regulator: core: Require regulator drivers to check uV for get_optimum_mode() 2022-08-25 17:58:32 +01:00
fs take care to handle NULL ->proc_lseek() 2022-08-14 15:16:18 -04:00
include regulator: Add devm helpers for get and enable 2022-08-18 12:51:48 +01:00
init Kbuild updates for v5.20 2022-08-10 10:40:41 -07:00
io_uring io_uring-6.0-2022-08-13 2022-08-13 13:28:54 -07:00
ipc Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
kernel xen: branch for v6.0-rc1b 2022-08-14 09:28:54 -07:00
lib lib: remove lib/nodemask.c 2022-08-12 09:07:33 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm - hugetlb_vmemmap cleanups from Muchun Song 2022-08-10 11:18:00 -07:00
net Including fixes from bluetooth, bpf, can and netfilter. 2022-08-11 13:45:37 -07:00
samples Tracing updates for 5.20 / 6.0 2022-08-05 09:41:12 -07:00
scripts RISC-V Patches for the 5.20 Merge Window, Part 2 2022-08-12 18:39:43 -07:00
security + Features 2022-08-10 10:53:22 -07:00
sound sound fixes for 6.0-rc1 2022-08-12 09:55:32 -07:00
tools perf tools changes for v6.0: 2nd batch 2022-08-14 09:22:11 -07:00
usr Not a lot of material this cycle. Many singleton patches against various 2022-05-27 11:22:03 -07:00
virt KVM: Actually create debugfs in kvm_create_vm() 2022-08-10 15:08:28 -04:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore kbuild: split the second line of *.mod into *.usyms 2022-05-08 03:16:59 +09:00
.mailmap Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS drm for 5.20/6.0 2022-08-03 19:52:08 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS regulator: drivers: Add TI TPS65219 PMIC regulators support 2022-08-23 18:13:09 +01:00
Makefile Linux 6.0-rc1 2022-08-14 15:50:18 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.