No description
Find a file
Hans de Goede de01ce3e40 pwm: lpss: Add range limit check for the base_unit register value
[ Upstream commit ef9f60daab ]

When the user requests a high enough period ns value, then the
calculations in pwm_lpss_prepare() might result in a base_unit value of 0.

But according to the data-sheet the way the PWM controller works is that
each input clock-cycle the base_unit gets added to a N bit counter and
that counter overflowing determines the PWM output frequency. Adding 0
to the counter is a no-op. The data-sheet even explicitly states that
writing 0 to the base_unit bits will result in the PWM outputting a
continuous 0 signal.

When the user requestes a low enough period ns value, then the
calculations in pwm_lpss_prepare() might result in a base_unit value
which is bigger then base_unit_range - 1. Currently the codes for this
deals with this by applying a mask:

	base_unit &= (base_unit_range - 1);

But this means that we let the value overflow the range, we throw away the
higher bits and store whatever value is left in the lower bits into the
register leading to a random output frequency, rather then clamping the
output frequency to the highest frequency which the hardware can do.

This commit fixes both issues by clamping the base_unit value to be
between 1 and (base_unit_range - 1).

Fixes: 684309e504 ("pwm: lpss: Avoid potential overflow of base_unit")
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200903112337.4113-5-hdegoede@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-29 09:07:05 +01:00
arch x86/fpu: Allow multiple bits in clearcpuid= parameter 2020-10-29 09:07:00 +01:00
block block: ensure bdi->io_pages is always initialized 2020-09-12 13:39:11 +02:00
certs Replace magic for trusting the secondary keyring with #define 2018-09-09 19:55:54 +02:00
crypto crypto: algif_skcipher - EBUSY on aio should be an error 2020-10-29 09:07:01 +01:00
Documentation x86/fpu: Allow multiple bits in clearcpuid= parameter 2020-10-29 09:07:00 +01:00
drivers pwm: lpss: Add range limit check for the base_unit register value 2020-10-29 09:07:05 +01:00
firmware Fix built-in early-load Intel microcode alignment 2020-01-23 08:20:30 +01:00
fs cifs: Return the error from crypt_message when enc/dec key not found. 2020-10-29 09:07:00 +01:00
include net/ipv4: always honour route mtu during forwarding 2020-10-29 09:06:58 +01:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:17:15 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:17:07 +02:00
kernel perf: Fix task_function_call() error handling 2020-10-14 09:51:14 +02:00
lib Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-10-14 09:51:10 +02:00
mm mm: khugepaged: recalculate min_free_kbytes after memory hotplug as expected by khugepaged 2020-10-14 09:51:14 +02:00
net icmp: randomize the global rate limiter 2020-10-29 09:06:59 +01:00
samples samples: bpf: Fix build error 2020-06-03 08:17:55 +02:00
scripts checkpatch: fix the usage of capture group ( ... ) 2020-09-09 19:03:13 +02:00
security ima: Don't ignore errors from crypto_shash_update() 2020-10-29 09:07:00 +01:00
sound ASoC: qcom: lpass-cpu: fix concurrency issue 2020-10-29 09:07:03 +01:00
tools perf top: Fix stdio interface input handling with glibc 2.28+ 2020-10-14 09:51:11 +02:00
usr initramfs: restore default compression behavior 2020-04-13 10:34:19 +02:00
virt KVM: fix overflow of zero page refcount with ksm running 2020-10-01 13:12:33 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild
Kconfig
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 16:36:12 +01:00
Makefile Linux 4.14.202 2020-10-17 10:29:55 +02:00
README

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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.