[Gta04-owner] New hw-validation snapshot

[Christoph Mair]

On Fri, Nov 18, 2011 at 11:08 AM, Neil Jerram <neil at ossau.homelinux.net> wrote:
> On 18.11.2011 09:35, Neil Jerram wrote:
>>
>> On 17.11.2011 09:35, Christoph Mair wrote:
>>
>>> Maybe its possible to boot use a initramfs to test the GPS reception.
>>> This would eliminate all activities on the mmc data lines.
>>
>> I'm willing to try this, but I don't understand how to implement your
>> suggestion.  Could you provide more detailed guidance?  (Or just point
>> me to some existing reference.)
>
> To be a bit more precise: I think I understand the idea of initramfs and how
> to create one, but
>
> (1) I can't see (looking at boot.txt) how I can tell u-boot to tell Linux to
> use an initramfs
>
> (2) I don't understand how this would eliminate MMC activity - because
> wouldn't the kernel and initramfs still be being loaded from the SD card?
>  (And I believe that MMC == SD, right?)

You're right. My thought was the following:
If the system is running from an initramfs the kernel won't touch the
SD card. If the rootfs is on the card it may uses it for whatever
reason (logging..).

Probably this could also be done with the u-boot test commands. If you
have access to the serial console, enter the u-boot command prompt and
type (from http://projects.goldelico.com/p/gta04-uboot/page/NewCommands)
$ gps init
$ gps on
$ gps echo

This dumps the raw GPS records to your serial terminal. If you get a
fix with this setup it could be possible that some other component
which is active when linux is running disturbs the gps reception (i.e.
mmc, display, ...)

Thanks your help,
  Christoph