[U-Boot] [PATCH U-Boot] ARM: rpi_b: detect board revision

Simon Glass sjg at chromium.org
Mon Nov 24 07:50:15 PST 2014

Hi Stephen,

On 18 November 2014 at 21:40, Stephen Warren <swarren at wwwdotorg.org> wrote:
> Detect the board revision early during boot, and print the decoded
> model name.
> Eventually, this information can be used for tasks such as:
> - Allowing/preventing USB device mode; some models have a USB device on-
>   board so only host mode makes sense. Others connect the SoC directly
>   to the USB connector, so device-mode might make sense.
> - The on-board USB hub/Ethernet requires different GPIOs to enable it,
>   although luckily the default appears to be fine so far.
> - The compute module contains an on-board eMMC device, so we could store
>   the environment there. Other models use an SD card and so don't support
>   saving the environment (unless we store it in a file on the FAT boot
>   partition...)
> Set $fdtfile based on this information. At present, the mainline Linux
> kernel doesn't contain a separate DTB for most models, but I hope that
> will change soon.
> Signed-off-by: Stephen Warren <swarren at wwwdotorg.org>
> ---
> I'm considering renaming rpi_b -> rpi in U-Boot since it supports many
> models. Hopefully I can persuade U-Boot to load the environment from
> different places at run-time, so we won't need different builds based
> on whether the environment is in eMMC or not for example.
>  arch/arm/include/asm/arch-bcm2835/mbox.h |  33 +++++++++
>  board/raspberrypi/rpi_b/rpi_b.c          | 122 ++++++++++++++++++++++++++++++-
>  include/configs/rpi_b.h                  |   1 -
>  3 files changed, 152 insertions(+), 4 deletions(-)

I tried this out. It worked OK for me except that it can't find the
device tree file bcm2835-rpi-b-rev2.dtb.

Oddly I can fatload it from /bcm2835-rpi-b-rev2.dtb but when I try
from /syslinux/..//bcm2835-rpi-b-rev2.dtb it fails and cannot find the
file. Reducing the filename length to 8 chars works. I wonder what
year of my life FAT will stop plaguing me?

Anyway this doesn't seem to be related to this patch, so:

Reviewed-by: Simon Glass <sjg at chromium.org>
Tested-by: Simon Glass <sjg at chromium.org>


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