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

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Submitter hvaibhav@ti.com
Date Sept. 18, 2012, 7:26 p.m.
Message ID <1347996365-17079-1-git-send-email-hvaibhav@ti.com>
Download mbox | patch
Permalink /patch/184853/
State Accepted
Delegated to: Tom Rini
Headers show

Comments

hvaibhav@ti.com - Sept. 18, 2012, 7:26 p.m.
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(-)
Tom Rini - Jan. 25, 2013, 10:10 p.m.
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!
hvaibhav@ti.com - Jan. 28, 2013, 3:44 a.m.
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

Patch

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" \