[Dev] Chromebook C201 wifi

Lee Strobel leestrobel at disroot.org
Tue Apr 2 10:23:06 GMT 2019 

Hi Josh,

I've got the $10 USB tester on order, should arrive in a few days. Once
I have that, hopefully I will be able to confirm whether or not the
power level is really the problem.

I will compare the ThinkPenguin dongle to the older Ralink one I have.
Also, the tester I've ordered has two split outputs (from the same port
on the laptop). So I should be able to plug in the wifi dongle; check
the current draw for that; then plug something else into the second
port on the tester (mouse, or phone charger or something). I should be
able to tell, based on whether the current increases when I do that,
whether or not the Penguin dongle is maxing out the available supply.

Regards,

Lee


On Mon, 2019-04-01 at 16:51 +0100, Josh Branning wrote:
> Hi just had a look and there doesn't appear to be an easy option,
> though 
> there are a few things that could help in u-boot by the looks of
> things, 
> I'm not too familiar with u-boot, and it would require probably
> require 
> someone who would know what they were doing to really help.
> 
> But I guess probably you'd need to compile u-boot, changing some
> stuff, 
> like grepping for "uA", "uV", "max-current" , "max-current" etc. have
> a 
> look at arch/arm/dts and see what's going in there etc. Probably
> there 
> is a main voltage regulator and a usb voltage regulator, someone who 
> knows about electronics could tell you if it could be a problem with 
> either, or just one or the other.
> 
> You could try typing "power info" from the prompt or something
> similar, 
> which may or may not show you usb current. Else, like you or someone 
> suggested, obtain a usb current and voltage meter and work out if
> that's 
> the issue for sure.
> 
> U-boot seems to be very board-specific which generally provides some 
> evidence against my original hypothesis, though it's difficult to
> tell. 
> Bare in mind, it could be a coincidence that both our arm devices
> are 
> struggling with USB and turn out not be power related at all, cheers,
> 
> Josh
> 
> On 31/03/19 21:24, Josh Branning wrote:
> > This is interesting, a while back I tried plugging in an external
> > HDD to 
> > an olinuxino (ARM) using parabola, and it didn't get enough power 
> > either. At that point, I assumed it was because the board wasn't 
> > providing the right power through the USB. I was using a power pack
> > that 
> > matched the recommended input voltage and current of the board.
> > 
> > Possibly a different thing entirely, but you never know ... there
> > could 
> > be some setting in the kernel or bootloader or something that means
> > the 
> > devices are only getting limited power through the USBs.
> > 
> > Another way to test if it is a parabola issue, could be to burn a
> > live 
> > CD or make a usb of a different distro, and see if the adapter
> > works 
> > with that, though if it is solely a bootloader issue, I guess that 
> > wouldn't be much help less a alternate one is also supplied. It is 
> > something I didn't do, because I assumed it would have probably
> > been the 
> > hardware simply being not able to supply required the power.
> > 
> > Note that on some other less-free similar dev boards, USB hdds
> > worked, 
> > albeit with a different distro. I know fosho that on some of these 
> > boards there is a bootloader setting where you can adjust the
> > output 
> > current/voltage, so there may be one in u-boot too.
> > 
> > Cheers,
> > 
> > Josh
> > 
> > On 31/03/19 20:43, Lee Strobel wrote:
> > > lsusb for the Senao EUB9801 says its max power is 450mA, so only
> > > 50mA
> > > less than the Atheros. However, I suspect those are just numbers
> > > someone's typed in a text file somewhere. They might not actually
> > > be
> > > drawing those currents.
> > > 
> > > It looks like a USB tester can be purchased online for $10. For
> > > that
> > > money, I might just buy one and actually measure the current
> > > draw.
> > > 
> > > Btw, from what I saw on Wikipedia, it looks like a standard usb
> > > 2.0
> > > port should be able to supply 500mA as standard.
> > > 
> > > Lee
> > > 
> > > 
> > > On Sun, 2019-03-31 at 14:04 -0400, Lee Strobel wrote:
> > > > Hi Denis,
> > > > 
> > > > > For the record, the WiFi related bugreport is here:
> > > > > https://labs.parabola.nu/issues/2261
> > > > > 
> > > > > Could you try to see if a USB HUB that is powered by its own
> > > > > power
> > > > > supply makes it usable. If you don't have one you may know
> > > > > people
> > > > > that
> > > > > have one and borrow it just for doing a quick test.
> > > > > 
> > > > 
> > > > I will see what I can do. I can't think of anyone I know off-
> > > > hand who
> > > > would have an externally-powered USB hub, but I will ask
> > > > around.
> > > > 
> > > > About the power thing: I actually have an older USB wifi
> > > > dongle, a
> > > > 'Senao EUB9801', which seems to work great when plugged
> > > > directly into
> > > > the Chromebook (if I use the firmware blob). According to the
> > > > kernel
> > > > boot log, I think it is running on a Ralink chip of some kind.
> > > > I will
> > > > try to investigate, as you suggested, and see if it requires
> > > > less
> > > > power
> > > > than the ThinkPenguin dongle. It is older (~8-10 years), so
> > > > maybe it
> > > > is
> > > > using an older wifi technology that consumes less power?
> > > > 
> > > > The reason I asked about the kernel devs is just because I was
> > > > wondering if the team that maintains the module for the Atheros
> > > > chip
> > > > are aware of the issue. I would think we might need their
> > > > assistance,
> > > > if any of us wanted to try to modify the module.
> > > > 
> > > > Lee
> > > > 
> > > > _______________________________________________
> > > > Dev mailing list
> > > > Dev at lists.parabola.nu
> > > > https://lists.parabola.nu/mailman/listinfo/dev
> > > 
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> > > 
> 
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