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Rajasingh Thavamani 232ba3a51c net: phy: Micrel KSZ8061: link failure after cable connect
With Micrel KSZ8061 PHY, the link may occasionally not come up after
Ethernet cable connect. The vendor's (Microchip, former Micrel) errata
sheet 80000688A.pdf descripes the problem and possible workarounds in
detail, see below.
The batch implements workaround 1, which permanently fixes the issue.

DESCRIPTION
Link-up may not occur properly when the Ethernet cable is initially
connected. This issue occurs more commonly when the cable is connected
slowly, but it may occur any time a cable is connected. This issue occurs
in the auto-negotiation circuit, and will not occur if auto-negotiation
is disabled (which requires that the two link partners be set to the
same speed and duplex).

END USER IMPLICATIONS
When this issue occurs, link is not established. Subsequent cable
plug/unplaug cycle will not correct the issue.

WORk AROUND
There are four approaches to work around this issue:
1. This issue can be prevented by setting bit 15 in MMD device address 1,
   register 2, prior to connecting the cable or prior to setting the
   Restart Auto-negotiation bit in register 0h. The MMD registers are
   accessed via the indirect access registers Dh and Eh, or via the Micrel
   EthUtil utility as shown here:
   . if using the EthUtil utility (usually with a Micrel KSZ8061
     Evaluation Board), type the following commands:
     > address 1
     > mmd 1
     > iw 2 b61a
   . Alternatively, write the following registers to write to the
     indirect MMD register:
     Write register Dh, data 0001h
     Write register Eh, data 0002h
     Write register Dh, data 4001h
     Write register Eh, data B61Ah
2. The issue can be avoided by disabling auto-negotiation in the KSZ8061,
   either by the strapping option, or by clearing bit 12 in register 0h.
   Care must be taken to ensure that the KSZ8061 and the link partner
   will link with the same speed and duplex. Note that the KSZ8061
   defaults to full-duplex when auto-negotiation is off, but other
   devices may default to half-duplex in the event of failed
   auto-negotiation.
3. The issue can be avoided by connecting the cable prior to powering-up
   or resetting the KSZ8061, and leaving it plugged in thereafter.
4. If the above measures are not taken and the problem occurs, link can
   be recovered by setting the Restart Auto-Negotiation bit in
   register 0h, or by resetting or power cycling the device. Reset may
   be either hardware reset or software reset (register 0h, bit 15).

PLAN
This errata will not be corrected in the future revision.

Fixes: 7ab59dc15e ("drivers/net/phy/micrel_phy: Add support for new PHYs")
Signed-off-by: Alexander Onnasch <alexander.onnasch@landisgyr.com>
Signed-off-by: Rajasingh Thavamani <T.Rajasingh@landisgyr.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-02-27 10:04:34 -08:00
arch Bug fixes. 2019-02-24 09:47:07 -08:00
block for-linus-20190215 2019-02-15 09:12:28 -08:00
certs kbuild: remove redundant target cleaning on failure 2019-01-06 09:46:51 +09:00
crypto net: crypto set sk to NULL when af_alg_release. 2019-02-18 12:01:24 -08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-02-24 09:28:26 -08:00
drivers net: phy: Micrel KSZ8061: link failure after cable connect 2019-02-27 10:04:34 -08:00
firmware kbuild: change filechk to surround the given command with { } 2019-01-06 09:46:51 +09:00
fs Two bug fixes for old issues, both marked for stable. 2019-02-21 09:43:37 -08:00
include net: dev: Use unsigned integer as an argument to left-shift 2019-02-27 09:34:39 -08:00
init revert "initramfs: cleanup incomplete rootfs" 2019-02-21 09:00:59 -08:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-02-24 09:28:26 -08:00
lib Merge branch 'fixes-v5.1-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-02-20 09:09:33 -08:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
mm mm, memory_hotplug: fix off-by-one in is_pageblock_removable 2019-02-21 09:01:01 -08:00
net tipc: fix race condition causing hung sendto 2019-02-26 14:50:50 -08:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-01-30 15:24:45 +01:00
scripts kallsyms: Handle too long symbols in kallsyms.c 2019-01-28 13:02:09 +09:00
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-02-24 09:28:26 -08:00
sound sound fixes for 5.0 2019-02-20 09:42:52 -08:00
tools selftests: fib_tests: sleep after changing carrier. again. 2019-02-23 18:34:20 -08:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt KVM/ARM fixes for 5.0: 2019-02-13 19:39:24 +01:00
.clang-format clang-format: Update .clang-format with the latest for_each macro list 2019-01-19 19:26:06 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support for DT binding schema checks 2018-12-13 09:41:32 -06:00
.mailmap A few early MIPS fixes for 4.21: 2019-01-05 12:48:25 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS CREDITS/MAINTAINERS: Retire parisc-linux.org email domain 2019-02-21 20:16:10 +01:00
Kbuild kbuild: use assignment instead of define ... endef for filechk_* rules 2019-01-06 10:22:35 +09:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-02-24 09:28:26 -08:00
Makefile Linux 5.0-rc7 2019-02-17 18:46:40 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.