Re: i.MX31 usb device support and power supply
Alan Stern <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Message-ID | <[email protected]> |
On Tue, 6 Mar 2007, Valentin Longchamp wrote: > Alan Stern wrote: > > > c->desc.bMaxPower is what the hub makes available for each port and > > > udev->bus_mA is what the device requests. > > > > It's the reverse: (c->desc.bMaxPower * 2) is what the device requests and > > udev->bus_mA is what the hub makes available. > > Ok. So the hub code rejects a device needing 150 mA (which resluts in 300) > althoug the MIC2536 is able to provide 150 mA. For me it rejects a > configuration that should be accepted, doestn't it ? No, no. If c->desc.bMaxPower == 150 then the device really needs 300 mA. Remember, the value in the descriptor is given in units of 2 mA. (That's how it manages to pack values ranging up to 500 in a single byte.) So the driver is rejecting a configuration which should be rejected. Alan Stern ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel