doc: Update docs for device tree in SPL, TPL

Make a few small updates to indicate that device tree can be used in SPL
and TPL.

Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Simon Glass 2018-10-01 12:22:17 -06:00
parent 343864afd7
commit a15a7aa47b
2 changed files with 12 additions and 1 deletions

View File

@ -174,6 +174,16 @@ After board configuration is done, fdt supported u-boot can be build in two ways
$ make DEVICE_TREE=<dts-file-name>
Relocation, SPL and TPL
-----------------------
U-Boot can be divided into three phases: TPL, SPL and U-Boot proper.
The full device tree is available to U-Boot proper, but normally only a subset
(or none at all) is available to TPL and SPL. See 'Pre-Relocation Support' and
'SPL Support' in doc/driver-model/README.txt for more details.
Limitations
-----------

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@ -832,7 +832,8 @@ Pre-Relocation Support
For pre-relocation we simply call the driver model init function. Only
drivers marked with DM_FLAG_PRE_RELOC or the device tree
'u-boot,dm-pre-reloc' flag are initialised prior to relocation. This helps
to reduce the driver model overhead.
to reduce the driver model overhead. This flag applies to SPL and TPL as
well, if device tree is enabled there.
It is possible to limit this to specific relocation steps, by using
the more specialized 'u-boot,dm-spl' and 'u-boot,dm-tpl' flags