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Siddaraju DH f0cf125056 ice: restrict PTP HW clock freq adjustments to 100, 000, 000 PPB 
[ Upstream commit 8aa4318c3a ]

The PHY provides only 39b timestamp. With current timing
implementation, we discard lower 7b, leaving 32b timestamp.
The driver reconstructs the full 64b timestamp by correlating the
32b timestamp with cached_time for performance. The reconstruction
algorithm does both forward & backward interpolation.

The 32b timeval has overflow duration of 2^32 counts ~= 4.23 second.
Due to interpolation in both direction, its now ~= 2.125 second
IIRC, going with at least half a duration, the cached_time is updated
with periodic thread of 1 second (worst-case) periodicity.

But the 1 second periodicity is based on System-timer.
With PPB adjustments, if the 1588 timers increments at say
double the rate, (2s in-place of 1s), the Nyquist rate/half duration
sampling/update of cached_time with 1 second periodic thread will
lead to incorrect interpolations.

Hence we should restrict the PPB adjustments to at least half duration
of cached_time update which translates to 500,000,000 PPB.

Since the periodicity of the cached-time system thread can vary,
it is good to have some buffer time and considering practicality of
PPB adjustments, limiting the max_adj to 100,000,000.

Signed-off-by: Siddaraju DH <siddaraju.dh@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-03-10 09:33:49 +01:00
arch x86/bugs: Reset speculation control settings on init 2023-03-10 09:33:49 +01:00
block blk-cgroup: synchronize pd_free_fn() from blkg_free_workfn() and blkcg_deactivate_policy() 2023-03-10 09:33:46 +01:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: rsa-pkcs1pad - Use akcipher_request_complete 2023-03-10 09:33:03 +01:00
Documentation ASoC: dt-bindings: meson: fix gx-card codec node regex 2023-03-10 09:33:19 +01:00
drivers ice: restrict PTP HW clock freq adjustments to 100, 000, 000 PPB 2023-03-10 09:33:49 +01:00
fs btrfs: scrub: improve tree block error reporting 2023-03-10 09:33:46 +01:00
include rcu: Make RCU_LOCKDEP_WARN() avoid early lockdep checks 2023-03-10 09:33:48 +01:00
init gcc: disable -Warray-bounds for gcc-11 too 2023-01-14 10:33:43 +01:00
io_uring use less confusing names for iov_iter direction initializers 2023-02-09 11:28:04 +01:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel timers: Prevent union confusion from unexpected restart_syscall() 2023-03-10 09:33:49 +01:00
lib cpuidle: lib/bug: Disable rcu_is_watching() during WARN/BUG 2023-03-10 09:33:47 +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 mm/gup: add folio to list when folio_isolate_lru() succeed 2023-02-22 12:59:54 +01:00
net inet: fix fast path in __inet_hash_connect() 2023-03-10 09:33:49 +01:00
rust rust: print: avoid evaluating arguments in pr_* macros in unsafe blocks 2023-02-06 08:06:34 +01:00
samples ftrace: Export ftrace_free_filter() to modules 2023-02-01 08:34:37 +01:00
scripts builddeb: clean generated package content 2023-03-10 09:33:41 +01:00
security randstruct: disable Clang 15 support 2023-02-25 11:25:43 +01:00
sound ALSA: hda/hdmi: Register with vga_switcheroo on Dual GPU Macbooks 2023-03-10 09:33:23 +01:00
tools bpftool: Always disable stack protection for BPF objects 2023-03-10 09:33:49 +01:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: Fix potential deadlock on vfio group_lock 2023-02-01 08:34:36 +01:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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 audit: update the mailing list in MAINTAINERS 2023-02-25 11:25:42 +01:00
Makefile Linux 6.1.15 2023-03-03 11:52:25 +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.