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    SubjectRe: [PATCH 1/2] USB: EHCI: Move sysfs related bits into ehci-sysfs.c
    On Wed, 29 Jun 2011, Kirill Smelkov wrote:

    > > Also, when decreasing the schedule limit, do you think it is really
    > > necessary to check that the current allocation doesn't exceed the new
    > > limit? I think it would be sufficient to apply the new limit just to
    > > new bandwidth allocation requests. After all, this API is meant for
    > > experts only.
    >
    > I think yes, it is needed. E.g. because there is this check in
    > periodic_usecs():
    >
    > #ifdef DEBUG
    > if (usecs > ehci->uframe_periodic_max)
    > ehci_err (ehci, "uframe %d sched overrun: %d usecs\n",
    > frame * 8 + uframe, usecs);
    > #endif
    > return usecs;
    > }
    >
    > and periodic_usecs() is called in e.g. this chain:
    >
    > itd_submit
    > iso_stream_schedule
    > itd_slot_ok
    > periodic_usecs
    >
    > and others.

    That won't matter unless DEBUG is defined.

    > I'd leave this check as is - to me it would be useful in debug mode to
    > verify that we've not overallocated a period.
    >
    > Also, even if this knob would be useful only to experts, it would be
    > better to put feedback onto the knob so that people could know whether
    > thir request could be served or not.
    >
    > What do you think?

    Can you make that check conditional on DEBUG being set?

    Alan Stern



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