[U-Boot] [PATCH] AM335X: Set fdt_high for AM335X devices to enable booting with Device Tree

For AM335X boards, such as the EVM and Bone Linux kernel fails to locate the device tree blob on boot. The reason being is that u-boot is copying the DT blob to the upper part of RAM when booting the kernel and the kernel is unable to access the blob. By setting the fdt_high variable to 0xffffffff (to prevent the copy) the kernel is able to locate the DT blob and boot.
This patch is tested on BeagleBone platform.
Signed-off-by: Vaibhav Hiremath hvaibhav@ti.com Cc: Tom Rini trini@ti.com --- include/configs/am335x_evm.h | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/include/configs/am335x_evm.h b/include/configs/am335x_evm.h index a3752bc..1af9b97 100644 --- a/include/configs/am335x_evm.h +++ b/include/configs/am335x_evm.h @@ -49,6 +49,7 @@ #define CONFIG_EXTRA_ENV_SETTINGS \ "loadaddr=0x80200000\0" \ "fdtaddr=0x80F80000\0" \ + "fdt_high=0xffffffff\0" \ "rdaddr=0x81000000\0" \ "bootfile=/boot/uImage\0" \ "console=ttyO0,115200n8\0" \

On Tue, Sep 18, 2012 at 09:26:05AM -0000, hvaibhav@ti.com wrote:
For AM335X boards, such as the EVM and Bone Linux kernel fails to locate the device tree blob on boot. The reason being is that u-boot is copying the DT blob to the upper part of RAM when booting the kernel and the kernel is unable to access the blob. By setting the fdt_high variable to 0xffffffff (to prevent the copy) the kernel is able to locate the DT blob and boot.
This patch is tested on BeagleBone platform.
Signed-off-by: Vaibhav Hiremath hvaibhav@ti.com Cc: Tom Rini trini@ti.com
So, a "funny" thing happened along the way since this patch. The newest revision of the EVM includes 1GB of DDR and thus we do now need this patch. Applied to u-boot-ti/master, thanks!

On Sat, Jan 26, 2013 at 03:40:51, Rini, Tom wrote:
On Tue, Sep 18, 2012 at 09:26:05AM -0000, hvaibhav@ti.com wrote:
For AM335X boards, such as the EVM and Bone Linux kernel fails to locate the device tree blob on boot. The reason being is that u-boot is copying the DT blob to the upper part of RAM when booting the kernel and the kernel is unable to access the blob. By setting the fdt_high variable to 0xffffffff (to prevent the copy) the kernel is able to locate the DT blob and boot.
This patch is tested on BeagleBone platform.
Signed-off-by: Vaibhav Hiremath hvaibhav@ti.com Cc: Tom Rini trini@ti.com
So, a "funny" thing happened along the way since this patch. The newest revision of the EVM includes 1GB of DDR and thus we do now need this patch. Applied to u-boot-ti/master, thanks!
Ohhh Great, Thanks for pulling in this patch Tom.
Thanks, Vaibhav
participants (3)
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Hiremath, Vaibhav
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Tom Rini
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Vaibhav Hiremath