Re: [linux-usb-devel] Re: What to do with all of the USB UHCI

[Maksim]

At 09:33 PM 5/21/2002 -0700, David Brownell wrote:
>Maksim (Max) Krasnyanskiy wrote:
>>One-shot interrupt transfers are broken in *-hcd drivers. core/hcd.c 
>>returns EINVAL if urb->interval==0.
><....>
>Meanwhile, I suppose I can see wanting access to that UHCI-ism.
>However your patch would do that wrong, since it should only
>apply to interrupt transfers.
Yeah, I guess it doesn't make sense to do one-shot iso.

>>On a side note. Why are URBs still not SLABified ?
>
>Hasn't seemed to be necessary.  kmalloc() is slabified already,
>so it's not clear that a control/bulk/interrupt URB pool shared
>between drivers -- size, maybe a handful -- would be better than
>sharing that same memory with other kernel code.
Well, kmalloc has slabs of a fixed size and will round requested amount
to the nearest value. For example on x86 sizeof(struct urb) == 84 which
will be rounded to 96 by kmalloc ie 12 bytes unused (on Sparc64 it's about 
20 bytes).
Also we could use slab constructor to pre-initialize some urb fields.

Max