On Thu, 18 Sep 2014 09:36:55 +1000
Julian Calaby <julian.cal...@gmail.com> wrote:

> Hi,
> 
> Earlier this year, HP released the following three tablets:
> (Australian store links due to the specifications listing the SoC's
> name)
> 
> HP 7 Plus: 
> http://h20386.www2.hp.com/AustraliaStore/Product.aspx?pdetail=P333853
> HP 8: http://h20386.www2.hp.com/AustraliaStore/Product.aspx?pdetail=P327832
> HP 10 Plus: 
> http://h20386.www2.hp.com/AustraliaStore/Product.aspx?pdetail=P339093
> 
> All of which appear to be based around the A31s SoC.
> 
> As they're pretty cheap for a "big name" brand's tablets, I'm planning
> to obtain one.
> 
> Has anyone else laid hands on any A31s devices yet? And if so, has any
> work started on supporting them?

I also have started considering to get an Allwinner based tablet
since a couple of weeks ago. So far all my devices are just various
development boards and one Mele TV box, which is not very different
from a development board in terms of features.

The first attempt was a failure. I tried to buy a relatively cheap 10"
no-name tablet (but with HDMI and 1GB of RAM), which was advertised
as Allwinner A20 by the seller. But it turned out to be in fact using
an Actions ATM7029B SoC with a quad-core Cortex-A5 CPU (disguised
as "Leopard Gen.I CPU core"). Big disappointment! And a total loss
of trust in this method of obtaining hardware. Though even if the
SoC was the right one, the build quality leaves a lot to be desired
and the screen is just horrible (colors and viewing angles). Maybe
other people had better experience, but I'm not going this route
again.

So now I'm also trying the "big name" brand buying strategy for a
change :-) The HP tablets look nice, but they don't have a HDMI
connector, which is a deal breaker for me. Another alternative are
some nice tablets from MSI. More specifically, these ones:
    http://www.msi.com/product/windpad/Primo_73.html#hero-specification
    http://www.msi.com/product/windpad/Primo_81.html#hero-specification
On a negative side, just like HP tablets, they have no bluetooth and
no dedicated charger connector. Primo 73 has a TN display (potentially
worse quality) and the Allwiner A20 SoC (worse performance than A31s,
but better support in linux-sunxi and no PowerVR).

HP provides nice service manuals for their tablets, for example
one can google for "HP 7 Plus Tablet and HP 7.1 Tablet Maintenance
and Service Guide". Which provides detailed instructions about how
to take them apart and replace components. It is interesting that
this  HP 7 Plus tablet is supposed to be equipped with 1.0-GB
LP-DDR2 (!) memory. If anyone has this hardware and can extract
the FEX file, it would be extremely interesting.

Regarding vendor firmware. MSI offers PhoenixSuite images for download
and also kernel sources from their website. This is very nice and
reassures the availability of FEL support for unbricking.
HP only provides updates as "update.zip" files to be copied on
the device and taken into use from the "android recovery" menu.
Not sure if this a bad sign and whether the FEL mode could be
locked out or not. Again, if anyone has an HP tablet, a
clarification about accessing FEL would be very much welcome.

Now one more thing about MSI tablets. Google searches for
"Primo 73 discontinued" and "Primo 81 discontinued" find a lot
of web shops, which are out of stock with the "discontinued
by manufacturer" explanation :-( On a somewhat positive side,
the remaining web shops still having these tablets in stock, seem
to be offering significant discounts at the moment (probably they
want to get rid of the inventory ASAP). For example
    http://www.newegg.com/Product/Product.aspx?Item=N82E16834152486
seems to offer MSI Primo 73 for $54.99. For the people from
Europe, some relatively interesting offers seem show up and
disappear on ebay.com rather quickly.

I myself have already ordered both Primo 73 and Primo 81 tablets (yeah,
this was a little bit hard on my budget and probably will prevent me
from buying new fun gadgets for a while). The tablets are expected to
arrive later this week. And then I'm going to post more information
about them to the mailing list.

Compared to plain development boards, tablets need properly working USB
OTG, touchscreens, WLAN and also power management features. This looks
like a lot of new fun :-)

Also the "big name" brand's tablets typically don't have a separate
power connector. They are using MicroUSB for both charging and
plugging USB peripherals. But there are things called "accessory
charging adapters (ACA)", and "By using an accessory charging
adapter, a device providing a single USB port can be attached to
both a charger, and another USB device at the same time":
    http://en.wikipedia.org/wiki/USB#ACA
I don't know if
    
http://www.ebay.co.uk/itm/4-Port-Micro-USB-Power-Charging-OTG-Hub-Adapter-Cable-for-HTC-LG-S4-Galaxy-Tab-3-/371135899746
is a proper compliant implementation of ACA or just has a switch
to enable the mode where 5V is provided on VBUS by the hub
(instead of feeding from VBUS). Either way, I'll try to see
if it can be used to provide power the tablet and allow using
USB peripherals connected to the hub at the same time.

Overall, these Allwinner A20/A31s tablets do not look very competitive
nowadays in terms of CPU performance and screen resolution, but might
be still an interesting choice for linux-sunxi enthusiasts.

-- 
Best regards,
Siarhei Siamashka

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