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Linux kernel for uConsole
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Julien Beraud a8bb9dd498 net: stmmac: Fix sub-second increment 
[ Upstream commit 91a2559c1d ]

In fine adjustement mode, which is the current default, the sub-second
    increment register is the number of nanoseconds that will be added to
    the clock when the accumulator overflows. At each clock cycle, the
    value of the addend register is added to the accumulator.
    Currently, we use 20ns = 1e09ns / 50MHz as this value whatever the
    frequency of the ptp clock actually is.
    The adjustment is then done on the addend register, only incrementing
    every X clock cycles X being the ratio between 50MHz and ptp_clock_rate
    (addend = 2^32 * 50MHz/ptp_clock_rate).
    This causes the following issues :
    - In case the frequency of the ptp clock is inferior or equal to 50MHz,
      the addend value calculation will overflow and the default
      addend value will be set to 0, causing the clock to not work at
      all. (For instance, for ptp_clock_rate = 50MHz, addend = 2^32).
    - The resolution of the timestamping clock is limited to 20ns while it
      is not needed, thus limiting the accuracy of the timestamping to
      20ns.

    Fix this by setting sub-second increment to 2e09ns / ptp_clock_rate.
    It will allow to reach the minimum possible frequency for
    ptp_clk_ref, which is 5MHz for GMII 1000Mps Full-Duplex by setting the
    sub-second-increment to a higher value. For instance, for 25MHz, it
    gives ssinc = 80ns and default_addend = 2^31.
    It will also allow to use a lower value for sub-second-increment, thus
    improving the timestamping accuracy with frequencies higher than
    100MHz, for instance, for 200MHz, ssinc = 10ns and default_addend =
    2^31.

v1->v2:
 - Remove modifications to the calculation of default addend, which broke
 compatibility with clock frequencies for which 2000000000 / ptp_clk_freq
 is not an integer.
 - Modify description according to discussions.

Signed-off-by: Julien Beraud <julien.beraud@orolia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-05-10 10:30:08 +02:00
arch powerpc/pci/of: Parse unassigned resources 2020-05-10 10:30:06 +02:00
block block, bfq: fix use-after-free in bfq_idle_slice_timer_body 2020-04-17 10:48:42 +02:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: api - Fix race condition in crypto_spawn_alg 2020-02-11 04:34:05 -08:00
Documentation arm64: errata: Hide CTR_EL0.DIC on systems affected by Neoverse-N1 #1542419 2020-04-29 16:31:08 +02:00
drivers net: stmmac: Fix sub-second increment 2020-05-10 10:30:08 +02:00
firmware Fix built-in early-load Intel microcode alignment 2020-01-23 08:21:29 +01:00
fs btrfs: transaction: Avoid deadlock due to bad initialization timing of fs_info::journal_info 2020-05-06 08:13:33 +02:00
include qed: Fix use after free in qed_chain_free 2020-05-02 17:26:00 +02:00
init fork: fix some -Wmissing-prototypes warnings 2019-12-05 09:21:04 +01:00
ipc ipc/util.c: sysvipc_find_ipc() should increase position index 2020-04-29 16:31:13 +02:00
kernel PM: hibernate: Freeze kernel threads in software_resume() 2020-05-06 08:13:28 +02:00
lib lib/raid6: use vdupq_n_u8 to avoid endianness warnings 2020-04-23 10:30:15 +02:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm: shmem: disable interrupt when acquiring info->lock in userfaultfd_copy path 2020-05-02 17:25:54 +02:00
net svcrdma: Fix leak of svc_rdma_recv_ctxt objects 2020-05-02 17:25:52 +02:00
samples vmalloc: fix remap_vmalloc_range() bounds checks 2020-04-29 16:31:27 +02:00
scripts kconfig: qconf: Fix a few alignment issues 2020-04-29 16:31:13 +02:00
security selinux: properly handle multiple messages in selinux_netlink_send() 2020-05-06 08:13:32 +02:00
sound ASoC: codecs: hdac_hdmi: Fix incorrect use of list_for_each_entry 2020-05-10 10:30:07 +02:00
tools selftests/ipc: Fix test failure seen after initial test run 2020-05-10 10:30:06 +02:00
usr initramfs: restore default compression behavior 2020-04-13 10:44:59 +02:00
virt x86/kvm: Cache gfn to pfn translation 2020-04-29 16:31:19 +02:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 16:38:49 +01:00
Makefile Linux 4.19.121 2020-05-06 08:13:35 +02:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
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.