On Thu, 10 Mar 2005 09:35:36 -0800, Nish Aravamudan
<[EMAIL PROTECTED]> wrote:
> On Wed, 9 Mar 2005 16:42:01 -0800, Greg KH <[EMAIL PROTECTED]> wrote:
> > ChangeSet 1.2035, 2005/03/09 10:12:19-08:00, [EMAIL PROTECTED]
> >
> > [PATCH] Add TPM hardware enablement driver
>
> <snip>
>
> > +void tpm_time_expired(unsigned long ptr)
> > +{
> > + int *exp = (int *) ptr;
> > + *exp = 1;
> > +}
> > +
> > +EXPORT_SYMBOL_GPL(tpm_time_expired);
>
> <snip>
>
> > + down(&chip->timer_manipulation_mutex);
> > + chip->time_expired = 0;
> > + init_timer(&chip->device_timer);
> > + chip->device_timer.function = tpm_time_expired;
> > + chip->device_timer.expires = jiffies + 2 * 60 * HZ;
> > + chip->device_timer.data = (unsigned long) &chip->time_expired;
> > + add_timer(&chip->device_timer);
> > + up(&chip->timer_manipulation_mutex);
> > +
> > + do {
> > + u8 status = inb(chip->vendor->base + 1);
> > + if ((status & chip->vendor->req_complete_mask) ==
> > + chip->vendor->req_complete_val) {
> > + down(&chip->timer_manipulation_mutex);
> > + del_singleshot_timer_sync(&chip->device_timer);
> > + up(&chip->timer_manipulation_mutex);
> > + goto out_recv;
> > + }
> > + set_current_state(TASK_UNINTERRUPTIBLE);
> > + schedule_timeout(TPM_TIMEOUT);
> > + rmb();
> > + } while (!chip->time_expired);
>
> <snip>
>
> It seems like this use of schedule_timeout() and the others are a bit
> excessive. In this case, a timer is set to go off in 2 hours or so,
> with tpm_time_expired() as the callback. tpm_time_expired(), it seems
> just takes data and sets it to 1, which in this case is
> chip->time_expired (and is similar in the other cases). We then loop
> while (!chip->time_expired), which to me means until
> chip->device_timer goes off, checking if the request is complete every
> 5 milliseconds. The chip->device_timer doesn't really do anything,
> does it? It just guarantees a maximum time (of 2 hours). Couldn't the
Sorry for the slight exaggeration :) Not 2 hours, but 2 minutes :)
still, a long time.
-Nish
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