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
same be achieved with (please excuse the lack of tabs, any real
patches I submit will have them):
unsigned long stop = jiffies + 2 * 60 * HZ;
do {
u8 status = inb(chip->vendor->base + 1);
if ((status & chip->vendor->req_complete_mask ==
chip->vendor->req_complete_val)
goto out_recv;
msleep(TPM_TIMEOUT); // TPM_TIMEOUT could now be 5 ms
rmb();
} while (time_before(jiffies, stop);
I think similar replacements would work in the other locations.
If people agree, I will send patches.
Thanks,
Nish
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