USB discussions getting a bit heated

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.

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.