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Filename Latest commit message Latest commit date
Martin Blumenstingl 433c6cab9d net: stmmac: dwmac-meson8b: fix setting the RGMII TX clock on Meson8b
Meson8b only supports MPLL2 as clock input. The rate of the MPLL2 clock
set by Odroid-C1's u-boot is close to (but not exactly) 500MHz. The
exact rate is 500002394Hz, which is calculated in
drivers/clk/meson/clk-mpll.c using the following formula:
DIV_ROUND_UP_ULL((u64)parent_rate * SDM_DEN, (SDM_DEN * n2) + sdm)
Odroid-C1's u-boot configures MPLL2 with the following values:
- SDM_DEN = 16384
- SDM = 1638
- N2 = 5

The 250MHz clock (m250_div) inside dwmac-meson8b driver is derived from
the MPLL2 clock. Due to MPLL2 running slightly faster than 500MHz the
common clock framework chooses a divider which is too big to generate
the 250MHz clock (a divider of 2 would be needed, but this is rounded up
to a divider of 3). This breaks the RTL8211F RGMII PHY on Odroid-C1
because it requires a (close to) 125MHz RGMII TX clock (on Gbit speeds,
the IP block internally divides that down to 25MHz on 100Mbit/s
connections and 2.5MHz on 10Mbit/s connections - we don't need any
special configuration for that).

Round the divider to the closest value to prevent this issue on Meson8b.
This means we'll now end up with a clock rate for the RGMII TX clock of
125001197Hz (= 125MHz plus 1197Hz), which is close-enough to 125MHz.
This has no effect on the Meson GX SoCs since there fclk_div2 is used as
input clock, which has a rate of 1000MHz (and thus is divisible cleanly
to 250MHz and 125MHz).

Fixes: 566e825162 ("net: stmmac: add a glue driver for the Amlogic Meson 8b / GXBB DWMAC")
Reported-by: Emiliano Ingrassia <ingrassia@epigenesys.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
Tested-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-01-17 14:41:05 -05:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-17 00:10:42 -05:00
block
certs
crypto
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-17 00:10:42 -05:00
drivers net: stmmac: dwmac-meson8b: fix setting the RGMII TX clock on Meson8b 2018-01-17 14:41:05 -05:00
firmware
fs
include net: sched: red: don't reset the backlog on every stat dump 2018-01-17 14:29:32 -05:00
init
ipc
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-17 00:10:42 -05:00
lib
mm
net net: sched: red: don't reset the backlog on every stat dump 2018-01-17 14:29:32 -05:00
samples samples/bpf: Fix trailing semicolon 2018-01-17 00:23:58 +01:00
scripts
security Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-17 00:10:42 -05:00
sound
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-17 00:10:42 -05:00
usr
virt
.cocciconfig
.get_maintainer.ignore
.gitattributes
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COPYING
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MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-01-17 00:10:42 -05:00
Makefile
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.