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Documentation: Various tweaks to user manual, device tree chapter. 

Grammar, typoes, font, link fixes.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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Robert P. J. Day 2014-07-03 08:00:07 -04:00 committed by Sascha Hauer
parent 4d62410b74
commit 1df8c9efbf
1 changed files with 15 additions and 14 deletions
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29
Documentation/user/devicetree.rst
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@ -4,29 +4,29 @@ Devicetree support
==================
Flattened Device Tree (FDT) is a data structure for describing the hardware on
a system. On an increasing number of boards both barebox and the Linux Kernel can
a system. On an increasing number of boards, both barebox and the Linux kernel can
probe their devices directly from devicetrees. barebox needs the devicetree compiled
into the binary. The Kernel usually does not have a devicetree compiled in, instead
the Kernel expects to be passed a devicetree from the bootloader.
into the binary. The kernel usually does not have a devicetree compiled in; instead,
the kernel expects to be passed a devicetree from the bootloader.
From a bootloader's point of view, using devicetrees has the advantage that the
same devicetree is used to probe both the Kernel and the Bootloader; this
same devicetree can be used by both the bootloader and the kernel; this
drastically reduces porting effort since the devicetree has to be written only
once (and with luck somebody has already written a devicetree for the Kernel).
Probing barebox from devicetree is highly recommended for new projects.
once (and with luck somebody has already written a devicetree for the kernel).
Having barebox consult a devicetree is highly recommended for new projects.
.. _internal_devicetree:
The internal devicetree
-----------------------
The devicetree barebox has been probed from plays a special role. It is referred to
as the :ref:`internal_devicetree`. The barebox devicetree commands work on this
devicetree. The devicetree source (DTS) files are kept in sync with the Kernel DTS
The devicetree consulted by barebox plays a special role. It is referred to
as the "internal devicetree." The barebox devicetree commands work on this
devicetree. The devicetree source (DTS) files are kept in sync with the kernel DTS
files. As the FDT files are meant to be backward compatible, it should always be possible
to start a Kernel with the barebox internal devicetree. However, since the barebox
to start a kernel with the barebox internal devicetree. However, since the barebox
devicetree may not be complete or contain bugs it is always possible to start the
Kernel with another devicetree than barebox has been started with.
kernel with a devicetree different from the one used by barebox.
If a device has been probed from the devicetree then using the :ref:`command_devinfo`
command on it will show the corresponding devicetree node:
@ -73,10 +73,11 @@ work on the internal devicetree. It is possible to add/remove nodes using the
It is important to know that these commands always work on the internal
devicetree. If you modify the internal devicetree to influence the behaviour of
a Kernel booted later, make sure that you start the kernel with the internal
a kernel booted later, make sure that you start the kernel with the internal
devicetree (i.e. don't pass a devicetree to the :ref:`command_bootm` command). If you
wish to use another devicetree than the internal devicetree for starting the Kernel,
you can exchange the internal devicetree during runtime:
wish to use another devicetree than the internal devicetree for starting the kernel,
you can exchange the internal devicetree during runtime using the
:ref:`command_oftree` command:
.. code-block:: sh