USB discussions getting a bit heated

David Harrison wrote:

 

I connected my bluetooth to my Mac and I get a power light.  When I connected it to my Pi nothing happened as before but while it was on I checked my voltage and it was 4.89 so at this point I'm not sure.  Any ideas

 

Cheers

David

Not having a Bluetooth ->Pi thinger going myself I can't be definitive, but I do recall a couple of threads on the other forum mentioning compatibility issues with certain Bluetooth devices (possibly regarding Broadcom chipsets, but my memory is rather less than optimal...). Might be worth having a search over there as well as asking here. The way that USB devices try to "negotiate" power over USB is quite complicated too, so it *may* simply fail to initialise because of insufficient current at connection (long story). This wouldn't be obvious with the average multimeter, which isn't sensitive to very quick events. Have you tried connecting via a powered hub (if you have one)?

Sorry I can't be more help.

Edit: - John beat me to it.

Hoping to get my powered usb soon so I can check this out.

Very comprehensive blog post here about USB 2.0 split transaction handling, which details the same USB data loss that RPF has described.  The article concerns a different SoC than used on the Pi, but still the same Synopsis core and OTG driver --- http://kynesim.blogspot.co.uk/2010/12/interesting-facts-about-usb-number-2312.html

There's a fairly new story about RasPi USB at Slashdot: Serious Problems with USB and Ethernet on the Raspberry Pi.  IIRC, most Slashdot coverage of RasPi has been very favorable.

I thought this comment was particularly interesting:

Anonymous Coward on Saturday August 25, @04:20AM (#41120815):

 

I work in a company who does SOC and we have one our SOC that use this USB core IP.

 

This USB core had so many problem that we end up making it work only in full speed mode [12 Mb/s] (and not high speed one [480 Mb/s]).  As you said split transaction don't work well (in our case we had seen IRQ storm that make linux freeze).

 

BTW we have full documentation of the chip (broadcom should have this), but the driver is so complex that it is very hard to fix/rewrite (AFAIK samsumg rewrite it).

 

Also for our newer SOC we used another USB IP made by chipidea, but the funny part is there were brought by synopsis and synopsis want people to buy there crappy dwc USB core...

Bold face and [editorial insertions] by yours truly.  As always with the Internet, you can't always believe Anonymous Cowards (or anybody else, including me), but this sounds pretty consistent with RasPi misbehaviour.

Aye, interesting.  That low-quality audio issue that I mentioned earlier -- http://www.element14.com/community/thread/19588?tstart=0 -- came from that same Slashdot thread.

Slashdot peeps aren't sure what to make of the Pi.  They recognize the hype and hold it in disdain for this as expected, but other than that the comments are pretty much a scattergun.

Re the USB controller, it appears to be the subject of universal condemnation.  It's really bad luck that the designer of the BCM2835 chose it in the first place, and then bad luck again that the designer of the Pi chose the BCM2835.  It's pretty clear that neither of them bothered to test the USB host functionality of that USB controller to any significant degree before giving it a green light.

PS. It's a bit late for RPF and in turn Broadcom to be passing the buck, but wasn't there a test coverage report accompanying the USB core when they bought it?  What happened to that?  Was it ever read by anyone?  Was the limited USB functionality signed off as good enough for the BCM2835's intended market?  Committing a chip design to fab is a serious and costly step and isn't generally done on a whim without a lot of detailed checks and sign-offs.

Am just having a look through the comments submitted to that Slashdot article. Users are a bit polarised, aren't they?

Getting rid of the polyfuses is good in the long run, as power supply issues have been the fall guy for just about everything. I see the closed SOC is coming in for some stick too. Bit of a red herring IMO. Unless folks are very lucky, a community fix for something as complex as the USB isn't going to happen. There might be a flurry of hacks in a situation like this, but it all just tends to be white noise which serves only to divert attention away from the people who's responsibility it is to actually fix the darn thing.

It is just a repurposed Roku SOC, after all.

Still, there has been progress of late on other fronts, so I'm happy to wait and see.

Edit: Morgaine beat me to the post! The whole situation reeks of  "It was fine when we tested it in the lab..." - the Fedora rollout was exactly the same. *Possibly* the best thing that ever happened to the Pi was that it was bought by an unsuspecting public who expected stuff to "just work". They then broke it in ways that the lab boys had never even considered and the faithful would never consider complaining about.

Perhaps this is why we haven't seen an absolute slew of Chinese clones yet - perhaps all but the most fly-by-night manufacturers are realising that there is merit in hardware that works out of the box* (allowing for the caveat that most far-eastern stuff is sold sans support).

*This is probably the most optimistic thing I've ever written.

Big thing the Roku box works !! (have a Roku 2 XS) and comes with a power supply, WiFi, pre-installed software, case, a remote control and you don't have to deal with "a sect" if you have problems with it.

Also I don't thing that replacing the polyfuses by 0 ohm resistors is a sign of progress, the keep the same arrogant attitude of not informing or letting the community participate and help, and I don't believe that serious testing has been done in "the lab" and claiming that RPF is a non-profit charity without the resources keeps being a lame excuse.

I still believe and said it many times, that the Rasperry Pi was/is a good idea, even with the Broadcom SoC, the problem is bad engineering and poor execution.

-J