Messages in this thread | | | Date | Mon, 23 Jun 2008 11:12:13 -0400 (EDT) | From | Alan Stern <> | Subject | Re: Scatter-gather list constraints |
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On Mon, 23 Jun 2008, David Vrabel wrote:
> Note that this 1024 byte multiple is for one particular WUSB mass > storage device. The WUSB standard permits max packet sizes of up 3584 > (in multiples of 512), but I suspect WUSB mass storage devices will only > use 512, 1024, or 2048. > > For a solution, we may be able to do something if the HWA host > controller is passed a single URB with an s-g list (rather than one URB > per s-g list entry) and was careful about how it segmented the URB into > transfers to the rpipe.
That would be ideal. However there is no way to pass an S-G list along with an URB; there's no field for it in the data structure. And none of the existing host controller drivers support such a thing.
I suppose we could add a field to struct urb and add a flag indicating whether the controller driver supports S-G lists.
Alan Stern
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