Igor,
On 19 Feb 2017, at 12:52, Igor Grinberg grinberg@compulab.co.il wrote:
On 02/17/17 19:28, Philipp Tomsich wrote:
This introduces the ability to override the environment offets from the device tree by setting the following nodes in '/config': 'u-boot,mmc-env-offset' - overrides CONFIG_ENV_OFFSET 'u-boot,mmc-env-offset-redundant' - overrides CONFIG_ENV_OFFSET_REDUND
To keep with the previous logic, the CONFIG_* defines still need to be available and the statically defined values become the defaults, when the corresponding properties are not set in the device-tree.
That sounds too odd... DT's purpose is to describe the h/w... and that does not look so... We also, have a dt file name in the environment, so this creates will create a chicken and an egg problem…
I don’t really follow… as far as I knew the DT name would have to come from some other source anyway, as the device containing the env might only be described through the device tree (e.g. mmc0).
U-Boot usually locates the FDT to use at a preconfigured address (or one configured in the early environment). This will not be the environment we’d load from a MMC device configured via DM_MMC.
So there shouldn’t be a chicken & egg here.
I really don't think we should go that direction. DT is not meant to provide a solution to all your problems...
I don’t see how this is different from other entries in chosen and config as of today: common/autoboot.c allows an override through /config/bootdelay common/board_r.c uses /config/load-environment common/cli.c can pull in /config/bootcmd drivers/serial/serial-uclass.c uses /chosen/stdout-path
In fact, it is the absence of this mechanism that is causing problems today: CONFIG_ENV_OFFSET is not configurable through Kconfig, so we would need board-specific defines (e.g. CONFIG_SUNXI_BOARD_LYNX) and matching #ifdef primitives in a shared header (sunxi-common.h in our case).
So putting this in the DT is the best (and least intrusive) option available.
Regards, Philipp.