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Douglas Anderson 607ccb7d3d clk: qcom: lpass-sc7280: Fix pm_runtime usage 
[ Upstream commit d470be3c4f ]

The pm_runtime usage in lpass-sc7280 was broken in quite a few
ways. Specifically:

1. At the end of probe it called "put" twice. This is a no-no and will
   end us up with a negative usage count. Even worse than calling
   "put" twice, it never called "get" once. Thus after bootup it could
   be seen that the runtime usage of the devices managed by this
   driver was -2.
2. In some error cases it manually called pm_runtime_disable() even
   though it had previously used devm_add_action_or_reset() to set
   this up to be called automatically. This meant that in these error
   cases we'd double-call pm_runtime_disable().
3. It forgot to call undo pm_runtime_use_autosuspend(), which can
   sometimes have subtle problems (and the docs specifically mention
   that you need to undo this function).

Overall the above seriously calls into question how this driver is
working. It seems like a combination of "it doesn't", "by luck", and
"because of the weirdness of runtime_pm". Specifically I put a
printout to the serial console every time the runtime suspend/resume
was called for the two devices created by this driver (I wrapped the
pm_clk calls). When I had serial console enabled, I found that the
calls got resumed at bootup (when the clk core probed and before our
double-put) and then never touched again. That's no good.
  [    0.829997] DOUG: my_pm_clk_resume, usage=1
  [    0.835487] DOUG: my_pm_clk_resume, usage=1

When I disabled serial console (speeding up boot), I got a different
pattern, which I guess (?) is better:
  [    0.089767] DOUG: my_pm_clk_resume, usage=1
  [    0.090507] DOUG: my_pm_clk_resume, usage=1
  [    0.151885] DOUG: my_pm_clk_suspend, usage=-2
  [    0.151914] DOUG: my_pm_clk_suspend, usage=-2
  [    1.825747] DOUG: my_pm_clk_resume, usage=-1
  [    1.825774] DOUG: my_pm_clk_resume, usage=-1
  [    1.888269] DOUG: my_pm_clk_suspend, usage=-2
  [    1.888282] DOUG: my_pm_clk_suspend, usage=-2

These different patterns have to do with the fact that the core PM
Runtime code really isn't designed to be robust to negative usage
counts and sometimes may happen to stumble upon a behavior that
happens to "work". For instance, you can see that
__pm_runtime_suspend() will treat any non-zero value (including
negative numbers) as if the device is in use.

In any case, let's fix the driver to be correct. We'll hold a
pm_runtime reference for the whole probe and then drop it (once!) at
the end. We'll get rid of manual pm_runtime_disable() calls in the
error handling. We'll also switch to devm_pm_runtime_enable(), which
magically handles undoing pm_runtime_use_autosuspend() as of commit
b4060db925 ("PM: runtime: Have devm_pm_runtime_enable() handle
pm_runtime_dont_use_autosuspend()").

While we're at this, let's also use devm_pm_clk_create() instead of
rolling it ourselves.

Note that the above changes make it obvious that
lpassaudio_create_pm_clks() was doing more than just creating
clocks. It was also setting up pm_runtime parameters. Let's rename it.

All of these problems were found by code inspection. I started looking
at this driver because it was involved in a deadlock that I reported a
while ago [1]. Though I bisected the deadlock to commit 1b771839de
("clk: qcom: gdsc: enable optional power domain support"), it was
never really clear why that patch affected it other than a luck of
timing changes. I'll also note that by fixing the timing (as done in
this change) we also seem to aboid the deadlock, which is a nice
benefit.

Also note that some of the fixes here are much the same type of stuff
that Dmitry did in commit 72cfc73f46 ("clk: qcom: use
devm_pm_runtime_enable and devm_pm_clk_create"), but I guess
lpassaudiocc-sc7280.c didn't exist then.

[1] https://lore.kernel.org/r/20220922154354.2486595-1-dianders@chromium.org

Fixes: a9dd26639d ("clk: qcom: lpass: Add support for LPASS clock controller for SC7280")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20221104064055.1.I00a0e4564a25489e85328ec41636497775627564@changeid
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-12-31 13:32:21 +01:00
arch x86/boot: Skip realmode init code when running as Xen PV guest 2022-12-31 13:32:16 +01:00
block block: clear ->slave_dir when dropping the main slave_dir reference 2022-12-31 13:32:12 +01:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto treewide: use get_random_bytes() when possible 2022-10-11 17:42:58 -06:00
Documentation ASoC: dt-bindings: wcd9335: fix reset line polarity in example 2022-12-31 13:32:18 +01:00
drivers clk: qcom: lpass-sc7280: Fix pm_runtime usage 2022-12-31 13:32:21 +01:00
fs NFS: Fix an Oops in nfs_d_automount() 2022-12-31 13:32:18 +01:00
include bpf, sockmap: Fix missing BPF_F_INGRESS flag when using apply_bytes 2022-12-31 13:32:20 +01:00
init init/Kconfig: fix CC_HAS_ASM_GOTO_TIED_OUTPUT test with dash 2022-11-22 22:42:38 +09:00
io_uring io_uring: Fix a null-ptr-deref in io_tctx_exit_cb() 2022-12-07 06:45:20 -07:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel bpf: Pin the start cgroup in cgroup_iter_seq_init() 2022-12-31 13:32:13 +01:00
lib lib/notifier-error-inject: fix error when writing -errno to debugfs file 2022-12-31 13:31:58 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
net wifi: cfg80211: Fix not unregister reg_pdev when load_builtin_regdb_keys() fails 2022-12-31 13:32:20 +01:00
rust Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
samples samples/bpf: Fix MAC address swapping in xdp2_kern 2022-12-31 13:32:03 +01:00
scripts - Handle different output of readelf on different distros running 2022-11-27 12:08:17 -08:00
security ima: Fix misuse of dereference of pointer in template_desc_init_fields() 2022-12-31 13:32:12 +01:00
sound ASoC: pcm512x: Fix PM disable depth imbalance in pcm512x_probe 2022-12-31 13:32:19 +01:00
tools netfilter: conntrack: set icmpv6 redirects as RELATED 2022-12-31 13:32:19 +01:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt Merge branch 'kvm-dwmw2-fixes' into HEAD 2022-11-23 18:59:45 -05:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
Makefile Linux 6.1.1 2022-12-21 17:48:12 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.