[Gta04-owner] GTA04 testing status

Peter Klassen neo.freerunner at googlemail.com
Tue Jun 28 22:07:34 CEST 2011


Am 28.06.2011 11:35, schrieb Dr. H. Nikolaus Schaller:
> A quick update: WiFi is now working.

woohoo, great news!

now lets cross the fingers for the UMTS module test :)

The things you have reached so far are huge!

Best
Peter

>> Now comes our problem child:
>>
>> :( WLAN/BT module
>>
>> It is recognized as mmc1 by the kernel and it appears that the
>> libertas_sdio driver loads and installs the firmware as expected.
>> But we get timeouts, i.e. no answer for real WLAN operation (e.g.
>> iwconfig, iwlist).
>>
>> And the chip gets unexpectedly hot. Bluetooth wasn't accessible
>> either.
>>
>> This needs a deep analysis and in the worst case we may have to
>> ship the early adopter boards without (working) WLAN/BT and fix
>> it in the GTA04A4. But before doing such a decision, we have to find
>> out what is going on.
> 
> It turned out to be a mixture of a hardware design bug, a chip supply bug
> and a software bug...
> 
> 1. we did not recognize correctly that albeit the WLAB/BT combo has
>     split supply for both components, it is not allowed to power up/down
>     them separately.
> 
>     This is a little tricky to fix, since two different LDOs are involved and
>     one is enabled *before* the CPU runs and the other one is enabled
>     by software (i.e. U-Boot).
> 
>     The workaround is to operate both from the CPU controlled LDO,
>     although we run it well beyond its maximum current specification. In
>     production we just have to rotate one ferrite inductor by 90 degrees...
> 
>     Well, for mass production this is not a good solution and we therefore
>     consider a separate LDO for the GTA04A4 layout.
> 
> 2. it turned out that there are different ROM mask versions of the
>     WLAN/BT combo. And our first sample chips are a version where
>     the BT chip has to be interfaced through USB. But we have no internal
>     USB port for this purpose and wired it up to a UART interface.
> 
>     The batch of chips we have bought for the early adopter boards have
>     a different and most likely the correct firmware, so BT should also work.
> 
>     We will replace one of the wrong chips with the right one to check the
>     HCI-UART interface (/dev/ttyS1) in the next days.
> 
> 3. We had seen timeouts on the SDIO command interface and initially
>     thought of another hardware problem (bad signal forms), but it turned
>     out that others had the same problem. And on the Rowboat mailing
>     list we found a hint that there is a bug in the libertas_sdio/omap_hsmmc
>     communication which makes the mmc driver to switch off some clock
>     at the wrong moment. After disabling this "feature", we were able to
>     scan for access points and event he sensitivity looks quite good.
>     
>     This "bug" may already have been solved by others in newer kernels
>     (we currently use a 2.6.32 kernel because it did work very well for
>     the core functions and e.g. display driver).
> 
> In summary, we will mount the WiFi/BT chip on the Early Adopter
> boards so that you can experiment with them.
> 
> One observation so far: power demand is quite high. The board draws
> approx. 250-300 mA while booting. And this goes up to 450-490 mA
> after WLAN is loaded and enabled. All this for a 1200 Ah battery...
> 
> So there will be a lot of areas for experimentation with kernel
> power management.
> 
> Next comes testing of the internal HSUSB for the UMTS modem.
> 
> -- N.
> 
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