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Pali Rohár 426c6cbc40 net: sfp: add workaround for Realtek RTL8672 and RTL9601C chips
The workaround for VSOL V2801F brand based GPON SFP modules added in commit
0d035bed2a ("net: sfp: VSOL V2801F / CarlitoxxPro CPGOS03-0490 v2.0
workaround") works only for IDs added explicitly to the list. Since there
are rebranded modules where OEM vendors put different strings into the
vendor name field, we cannot base workaround on IDs only.

Moreover the issue which the above mentioned commit tried to work around is
generic not only to VSOL based modules, but rather to all GPON modules
based on Realtek RTL8672 and RTL9601C chips.

These include at least the following GPON modules:
* V-SOL V2801F
* C-Data FD511GX-RM0
* OPTON GP801R
* BAUDCOM BD-1234-SFM
* CPGOS03-0490 v2.0
* Ubiquiti U-Fiber Instant
* EXOT EGS1

These Realtek chips have broken EEPROM emulator which for N-byte read
operation returns just the first byte of EEPROM data, followed by N-1
zeros.

Introduce a new function, sfp_id_needs_byte_io(), which detects SFP modules
with broken EEPROM emulator based on N-1 zeros and switch to 1 byte EEPROM
reading operation.

Function sfp_i2c_read() now always uses single byte reading when it is
required and when function sfp_hwmon_probe() detects single byte access,
it disables registration of hwmon device, because in this case we cannot
reliably and atomically read 2 bytes as is required by the standard for
retrieving values from diagnostic area.

(These Realtek chips are broken in a way that violates SFP standards for
diagnostic interface. Kernel in this case simply cannot do anything less
of skipping registration of the hwmon interface.)

This patch fixes reading of EEPROM content from SFP modules based on
Realtek RTL8672 and RTL9601C chips. Diagnostic interface of EEPROM stays
broken and cannot be fixed.

Fixes: 0d035bed2a ("net: sfp: VSOL V2801F / CarlitoxxPro CPGOS03-0490 v2.0 workaround")
Co-developed-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-01-28 13:41:17 -08:00
Documentation devlink: Add DMAC filter generic packet trap 2021-01-27 19:53:40 -08:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
arch arm64: dts: qcom: sdm845: kill IPA modem-remoteproc property 2021-01-21 20:42:46 -08:00
block block-5.11-2021-01-10 2021-01-10 12:53:08 -08:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto X.509: Fix crash caused by NULL pointer 2021-01-20 11:33:51 -08:00
drivers net: sfp: add workaround for Realtek RTL8672 and RTL9601C chips 2021-01-28 13:41:17 -08:00
fs cachefiles: Drop superfluous readpages aops NULL check 2021-01-20 11:33:51 -08:00
include net/mlx5e: Add trap entity to ETH driver 2021-01-27 19:53:53 -08:00
init Revert "init/console: Use ttynull as a fallback when there is no console" 2021-01-08 11:02:18 -08:00
ipc Merge branch 'akpm' (patches from Andrew) 2020-12-15 12:53:37 -08:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-01-20 12:16:11 -08:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2021-01-20 12:16:11 -08:00
mm mm: don't put pinned pages into the swap cache 2021-01-17 12:08:04 -08:00
net net: reduce indentation level in sk_clone_lock() 2021-01-28 11:02:39 -08:00
samples bpf: Rename BPF_XADD and prepare to encode other atomics in .imm 2021-01-14 18:34:29 -08:00
scripts Kbuild fixes for v5.11 2021-01-10 13:24:55 -08:00
security dump_common_audit_data(): fix racy accesses to ->d_name 2021-01-16 15:11:35 -05:00
sound ALSA: hda/hdmi - enable runtime pm for CI AMD display audio 2021-01-12 16:06:01 +01:00
tools selftests: increase timeout to 10 min 2021-01-27 16:53:55 -08:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt x86: 2021-01-08 15:06:02 -08:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap MAINTAINERS: Update my email address 2021-01-15 23:55:16 +01:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: dccp: move Gerrit Renker to CREDITS 2021-01-14 10:53:49 -08:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add entry for Arrow SpeedChips XRS7000 driver 2021-01-21 13:00:08 -08:00
Makefile net: move CONFIG_NET guard to top Makefile 2021-01-27 17:03:52 -08:00
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.