[Gta04-owner] New hw-validation snapshot

Boudewijn wankelwankel at yahoo.com
Fri Nov 18 14:16:28 CET 2011


On Friday 18 November 2011 11:13:00 Christoph Mair wrote:
> 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, ...)
 
It may be worth a go of course, but I think Nikolaus meant more in general 
that if there's a (hardware) problem with an easy workaround, that does not 
mean that the cause to the symptoms is easily identified.

In case of MMC: it's not only used for connecting SD/MMC cards, but for WIFI 
as well, isn't it? Of course the initramfs would have no need for WIFI either, 
and if ran from NAND it will exclude as many other factors as possible, but 
it's still prodding with a stick in the dark.

For wat it's worth, I just downloaded the new kernel and configs.. Who knows 
;-)

Boudewijn
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