Andre Przywara 602cfd269e arm64: dts: juno: Fix UART frequency
[ Upstream commit 39a1a8941b27c37f79508426e27a2ec29829d66c ]

Older versions of the Juno *SoC* TRM [1] recommended that the UART clock
source should be 7.2738 MHz, whereas the *system* TRM [2] stated a more
correct value of 7.3728 MHz. Somehow the wrong value managed to end up in
our DT.

Doing a prime factorisation, a modulo divide by 115200 and trying
to buy a 7.2738 MHz crystal at your favourite electronics dealer suggest
that the old value was actually a typo. The actual UART clock is driven
by a PLL, configured via a parameter in some board.txt file in the
firmware, which reads 7.37 MHz (sic!).

Fix this to correct the baud rate divisor calculation on the Juno board.

[1] http://infocenter.arm.com/help/topic/com.arm.doc.ddi0515b.b/DDI0515B_b_juno_arm_development_platform_soc_trm.pdf
[2] http://infocenter.arm.com/help/topic/com.arm.doc.100113_0000_07_en/arm_versatile_express_juno_development_platform_(v2m_juno)_technical_reference_manual_100113_0000_07_en.pdf

Fixes: 71f867ec130e ("arm64: Add Juno board device tree.")
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-01-27 14:46:53 +01:00
2020-01-27 14:46:53 +01:00
2020-01-27 14:46:52 +01:00
2020-01-27 14:46:19 +01:00

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.
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