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authorTom Rini <trini@konsulko.com>2018-11-16 08:37:50 -0500
committerTom Rini <trini@konsulko.com>2018-11-16 08:37:50 -0500
commit1d6edcbfed2af33c748f2beb399810a0441888da (patch)
treefe88d63e5ef1dbe1915f90e02429e8b6934859da /doc/driver-model
parentf6206f8587fc7ec82a57dbbeb5de0f94b3c2ef49 (diff)
parent4c6e27f63c88d065a98f438085dfc36af47d3a23 (diff)
Merge tag 'pull-14nov18' of git://git.denx.de/u-boot-dm
- virtio implementation and supporting patches - DM_FLAG_PRE_RELOC fixes - regmap improvements - minor buildman and sandbox things
Diffstat (limited to 'doc/driver-model')
-rw-r--r--doc/driver-model/README.txt16
1 files changed, 12 insertions, 4 deletions
diff --git a/doc/driver-model/README.txt b/doc/driver-model/README.txt
index 36541630a2..07b120d512 100644
--- a/doc/driver-model/README.txt
+++ b/doc/driver-model/README.txt
@@ -830,10 +830,18 @@ 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. This flag applies to SPL and TPL as
-well, if device tree is enabled there.
+drivers marked with DM_FLAG_PRE_RELOC or the device tree 'u-boot,dm-pre-reloc'
+property are initialised prior to relocation. This helps to reduce the driver
+model overhead. This flag applies to SPL and TPL as well, if device tree is
+enabled (CONFIG_OF_CONTROL) there.
+
+Note when device tree is enabled, the device tree 'u-boot,dm-pre-reloc'
+property can provide better control granularity on which device is bound
+before relocation. While with DM_FLAG_PRE_RELOC flag of the driver all
+devices with the same driver are bound, which requires allocation a large
+amount of memory. When device tree is not used, DM_FLAG_PRE_RELOC is the
+only way for statically declared devices via U_BOOT_DEVICE() to be bound
+prior to relocation.
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