> -----Original Message----- > From: Alan Stern [mailto:stern@xxxxxxxxxxxxxxxxxxx] > Sent: Wednesday, July 20, 2011 3:27 AM > To: Sebastian Andrzej Siewior > Cc: Xu, Andiry; greg@xxxxxxxxx; linux-usb@xxxxxxxxxxxxxxx > Subject: Re: [PATCH v4] usbcore: get BOS descriptor set > > On Tue, 19 Jul 2011, Sebastian Andrzej Siewior wrote: > > > * Andiry Xu | 2011-07-18 16:43:51 [+0800]: > > > > >This commit gets BOS(Binary Device Object Store) descriptor set for > Super > > >Speed devices and High Speed devices which support BOS descriptor. > > > > > >BOS descriptor is used to report additional USB device-level > capabilities > > >that are not reported via the Device descriptor. By getting BOS > descriptor > > >set, driver can check device's device-level capability such as LPM > > >capability. > > > > > >Signed-off-by: Andiry Xu <andiry.xu@xxxxxxx> > > > > Looks good. > > Looks good to me too. > > Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > Thanks for the ack. However, I found that when connect a USB3 device (Buffalo HD-HXU3) via a USB2 cable to a xHCI host, it's bcdUSB field is 0x0201. Since the check condition is bcdUSB >= 0x0210, driver does not fetch BOS descriptors. Another USB3 device (Kingston DT Ultimate) reports 0x0210 when connected via USB2 cable, and driver fetches BOS descriptor. The value I used is from USB3 spec 9.2.6.6, which says "Devices with a value of at least 0210H in the bcdUSB field of their device descriptor shall support GetDescriptor (BOS descriptor) requests". However, I checked USB2 LPM spec Chapt 3, which says: "Devices that support the BOS descriptor must have a bcdUSB value of 0201H or larger." Is this a conflict? Which value should I use, 0x0201 or 0x0210? Thanks, Andiry -- 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
