Johannes Erdfelt wrote:
>
> On Fri, Jun 16, 2000, Dunlap, Randy <[EMAIL PROTECTED]> wrote:
> > I got a CTX monitor/hub this week and spent today
> > looking into this problem. The problem is that
> > the hub doesn't like to return a partial descriptor
> > in usb_hub_configure() [2-byte "header" is requested].
> >
> > I have made 2 workarounds for this and either one
> > of them works, but I'd like your opinion on them,
> > then one of us can make a patch to hub.c.
> >
> > A. Do the normal 2-byte header request, then handle
> > this error case (something like):
> >
> > if (ret == -EPIPE &&
> > (vendor == CTX) && (product == 0x9999)) {
> > /* simulate good desc & clear the stall */
> > bLength = 2;
> > bDescType = USB_DT_HUB;
> > if (usb_clear_halt(dev, usbrcvctrlpipe(dev, 0)))
> > return -1;
> > }
> > ...
> >
> > . More direct, less intrusive to the current code.
> >
> > or:
> >
> > B. Don't do a 2-byte header request; do a header request
> > of 13 bytes [or maybe even larger, but 13 bytes is enough
> > for a 16-port hub]. This requires only one get_hub_desc()
> > call instead of 2. Instead of the 2nd call, just
> > memcpy (bitmap, buffer, header->bLength).
> > [Think we'll ever need to support more than 16 ports on
> > a hub?]
> >
> > . More general solution [unless we find some hub that doesn't
> > like descriptor requests that are _larger_ than actual].
> > . Calls get_hub_desc() one time instead of 2 times.
> >
> > I tested both methods with a keyboard and floppy drive
> > on UHCI (both HCDs) and OHCI.
> >
> > Which method do you prefer? Do you want to make a hub.c
> > patch for this or have me do it? I'll be glad to send
> > my patches to you, of course.
>
> I like option B, but why don't we just request 39 bytes?
>
> That's 7 bytes for the base hub descriptor, 16 bytes for DeviceRemovable
> (127 ports) and 16 bytes for PortPwrCtrlMask (127 ports).
Any reason why you chose 127?
Table 11-8 of USB Spec Rev 1.1 says "maximum of 255 ports". So that
should be 7+32+32 or about 71 bytes requested.
Brad
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