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Filename Latest commit message Latest commit date
Ahmad Fatoum 7159a27b1a clk: imx: composite-8m: fix clock pauses when set_rate would be a no-op
[ Upstream commit 4dd432d985ef258e3bc436e568fba4b987b59171 ]

Reconfiguring the clock divider to the exact same value is observed
on an i.MX8MN to often cause a longer than usual clock pause, probably
because the divider restarts counting whenever the register is rewritten.

This issue doesn't show up normally, because the clock framework will
take care to not call set_rate when the clock rate is the same.
However, when we reconfigure an upstream clock, the common code will
call set_rate with the newly calculated rate on all children, e.g.:

  - sai5 is running normally and divides Audio PLL out by 16.
  - Audio PLL rate is increased by 32Hz (glitch-free kdiv change)
  - rates for children are recalculated and rates are set recursively
  - imx8m_clk_composite_divider_set_rate(sai5) is called with
    32/16 = 2Hz more
  - imx8m_clk_composite_divider_set_rate computes same divider as before
  - divider register is written, so it restarts counting from zero and
    MCLK is briefly paused, so instead of e.g. 40ns, MCLK is low for 120ns.

Some external clock consumers can be upset by such unexpected clock pauses,
so let's make sure we only rewrite the divider value when the value to be
written is actually different.

Fixes: d3ff972813 ("clk: imx: Add imx composite clock")
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20230807082201.2332746-1-a.fatoum@pengutronix.de
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-09-23 10:59:47 +02:00
arch arm64: dts: qcom: sdm845: Add missing RPMh power domain to GCC 2023-09-23 10:59:45 +02:00
block block/partition: fix signedness issue for Amiga partitions 2023-07-27 08:37:29 +02:00
certs
crypto KEYS: asymmetric: Copy sig and digest in public_key_verify_signature() 2023-06-21 15:44:08 +02:00
Documentation Documentation/sysctl: document page_lock_unfairness 2023-08-30 16:27:27 +02:00
drivers clk: imx: composite-8m: fix clock pauses when set_rate would be a no-op 2023-09-23 10:59:47 +02:00
fs quota: fix dqput() to follow the guarantees dquot_srcu should provide 2023-09-23 10:59:43 +02:00
include lwt: Check LWTUNNEL_XMIT_CONTINUE strictly 2023-09-23 10:59:42 +02:00
init x86/mm: Initialize text poking earlier 2023-08-08 19:56:36 +02:00
ipc ipc/sem: Fix dangling sem_array access in semtimedop race 2022-12-08 11:23:06 +01:00
kernel audit: fix possible soft lockup in __audit_inode_child() 2023-09-23 10:59:46 +02:00
lib radix tree: remove unused variable 2023-08-30 16:27:26 +02:00
LICENSES
mm tmpfs: verify {g,u}id mount options correctly 2023-09-23 10:59:40 +02:00
net netrom: Deny concurrent connect(). 2023-09-23 10:59:43 +02:00
samples samples/bpf: Fix buffer overflow in tcp_basertt 2023-07-27 08:37:07 +02:00
scripts modpost: fix off by one in is_executable_section() 2023-07-27 08:37:18 +02:00
security smackfs: Prevent underflow in smk_set_cipso() 2023-09-23 10:59:46 +02:00
sound ALSA: ac97: Fix possible error value of *rac97 2023-09-23 10:59:46 +02:00
tools selftests: mirror_gre_changes: Tighten up the TTL test match 2023-08-30 16:27:16 +02:00
usr
virt KVM: Destroy target device if coalesced MMIO unregistration fails 2023-03-11 16:44:01 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS iio: stx104: Move to addac subdirectory 2023-08-30 16:27:12 +02:00
Makefile Linux 5.4.256 2023-09-02 09:19:19 +02:00
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.