On Mon, Sep 14, 2009 at 10:11:51PM +0400, Sergei Shtylyov wrote: > Hello, I wrote: > > >>> I still don't get why USB_OTG_DRV_VBUS exists, as well as the > >>>pulldown flags -- these pulldowns are a part of USB/OTG protocol, so > >>>any fixed setting hardly makes sense... > > >>Hmm. I thought this lets you decide whether you use the internal > >>pulls or use external ones. > > > And you were right -- 1.5K Ohm pullups are used on device side to > >signal the speed. Host side does use 15K Ohm pulldowns. I've mixed > >everything up, so rry about that. :-) > > >>How would the OTG core alter the behaviour > >>then? Which code would be missing to support it the way the OTG stack > >>works? > > OK, I have got my hands on the OTG spec. 1.3 PDF now -- there's > some difference with the pure host mode WRT data line pulldowns: > > << > 5.1.6 Data Line Pull-down Resistance > > When an A-device is idle or acting a s a Host, it shall activate > pull-*down resistors on both D+ and D- lines. These resistors shall > be within the range of 14.25 kOhm to 24.5 kOhm (Rpd). > > When an A-device is acting as a Peripheral, it shall disable the > pull-down on the D+ line but shall not disable the pull-down on D- > line. Maintaining a pull-down on the D- line prevents the A-device > D- line from floating if the B-device becomes unplugged. An > On-The-Go A-device is allowed to disable both pull-down resistors > during the interval of a packet transmission while acting as either > Host or Periperal. > >> > > > I don't have the OTG spec. at hand (or in any digital form), and > >my > > It turned out that I do have it in digital form, on a work PC. :-) > > >memories of the reading are fragmented ATM... :-/ Will try to gfet > >my hands on the printout again... > > HNP operates using data line pull up, so I must have misremembered here too. > > > Well, still not clear about the ID pullup/sampling -- do you > >want to be able to suppress that fro the board code too? Without > >this, it's basically not OTG anymore. > > Could be useful to force host only mode though... Sorry for the long delay on this. I got distracted for some weeks and admittedly lost track on this issue a little. Could you rephrase the current status of this from your side again? Is the code generic enough to go in? I'd love to bring this to an end finally, and can work on it next week. Thanks, Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
