Boards which use DCD data in SCFW can drop SPL.
We tried in our mainline rework to use this approach too as other imx8qxp boards do in mainline. But we failed ... it was a hard way to understand the reason!
We cannot use DCD image in container as the SCFW from siemens, does the RAM init on boot itself!
Siemens SCFW reads the RAM config from i2c eeprom and dependent on this settings, initializes the RAM.
Adding DCD data to the bootcontainer will result in hang of the SCFW, also DCD data in container image is static which do not fit our needs.
So we must drop DCD data image, and this has the side effect that we need SPL, as the task which loads the images from the container only loads the images to addresses, and if executed bit is set, starts them.
As now RAM is not initialized from it, and there is no option to "wait until SCFW has setup RAM", we can only load SPL into internal RAM at this point, as than SPL and SCFW boot parallel.
The SPL itself than uses the SCU API to communicate with the SCFW and it seems that SCFW only responds to this API requests when RAM setup is already done by the SCFW, which has a side-effect of a "sync" for the RAM setup is done by SCFW!
We checked if SPL is always save in accessing RAM for loading images to it! For tests, we added in our RAM init part in the SCFW long delays (10 seconds and more) as we thought there is such a sync missing, and we can break the board through delaying RAM setup... but we did not managed to fail booting U-Boot from SPL!
Signed-off-by: Heiko Schocher hs@denx.de ---
board/siemens/capricorn/imximage.cfg | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/board/siemens/capricorn/imximage.cfg b/board/siemens/capricorn/imximage.cfg index 4350e2967cc..e45f2c9589e 100644 --- a/board/siemens/capricorn/imximage.cfg +++ b/board/siemens/capricorn/imximage.cfg @@ -9,6 +9,10 @@
/* Boot from SD, sector size 0x400 */ BOOT_FROM sd + +/* skip DCD data, as firmware initializes the RAM */ +DCD_SKIP true + /* SoC type IMX8QX */ SOC_TYPE IMX8QX /* Append seco container image */